Provided by: python3-intake_0.6.5-2_amd64 
NAME
intake - Intake Documentation
Taking the pain out of data access and distribution
Intake is a lightweight package for finding, investigating, loading and disseminating
data. It will appeal to different groups for some of the reasons below, but is useful for
all and acts as a common platform that everyone can use to smooth the progression of data
from developers and providers to users.
Intake contains the following main components. You do not need to use them all! The
library is modular, only use the parts you need:
• A set of data loaders (Drivers) with a common interface, so that you can investigate or
load anything, from local or remote, with the exact same call, and turning into data
structures that you already know how to manipulate, such as arrays and data-frames.
• A Cataloging system (Catalogs) for listing data sources, their metadata and parameters,
and referencing which of the Drivers should load each. The catalogs for a hierarchical,
searchable structure, which can be backed by files, Intake servers or third-party data
services
• Sets of convenience functions to apply to various data sources, such as data-set
persistence, automatic concatenation and metadata inference and the ability to
distribute catalogs and data sources using simple packaging abstractions.
• A GUI layer accessible in the Jupyter notebook or as a standalone webserver, which
allows you to find and navigate catalogs, investigate data sources, and plot either
predefined visualisations or interactively find the right view yourself
• A client-server protocol to allow for arbitrary data cataloging services or to serve the
data itself, with a pluggable auth model.
DATA USER
• Intake loads the data for a range of formats and types (see plugin-directory) into
containers you already use, like Pandas dataframes, Python lists, NumPy arrays, and more
• Intake loads, then gets out of your way
• GUI search and introspect data-sets in Catalogs: quickly find what you need to do your
work
• Install data-sets and automatically get requirements
• Leverage cloud resources and distributed computing.
See the executable tutorial:
https://mybinder.org/v2/gh/intake/intake-examples/master?filepath=tutorial%2Fdata_scientist.ipynb
DATA PROVIDER
• Simple spec to define data sources
• Single point of truth, no more copy&paste
• Distribute data using packages, shared files or a server
• Update definitions in-place
• Parametrise user options
• Make use of additional functionality like filename parsing and caching.
See the executable tutorial:
https://mybinder.org/v2/gh/intake/intake-examples/master?filepath=tutorial%2Fdata_engineer.ipynb
IT
• Create catalogs out of established departmental practices
• Provide data access credentials via Intake parameters
• Use server-client architecture as gatekeeper:
• add authentication methods
• add monitoring point; track the data-sets being accessed.
• Hook Intake into proprietary data access systems.
DEVELOPER
• Turn boilerplate code into a reusable Driver
• Pluggable architecture of Intake allows for many points to add and improve
• Open, simple code-base -- come and get involved on github!
See the executable tutorial:
https://mybinder.org/v2/gh/intake/intake-examples/master?filepath=tutorial%2Fdev.ipynb
The start document contains the sections that all users new to Intake should read through.
usecases shows specific problems that Intake solves. For a brief demonstration, which you
can execute locally, go to quickstart. For a general description of all of the components
of Intake and how they fit together, go to overview. Finally, for some notebooks using
Intake and articles about Intake, go to examples and intake-examples. These and other
documentation pages will make reference to concepts that are defined in the glossary.
START HERE
These documents will familiarise you with Intake, show you some basic usage and examples,
and describe Intake's place in the wider python data world.
Quickstart
This guide will show you how to get started using Intake to read data, and give you a
flavour of how Intake feels to the Data User. It assumes you are working in either a
conda or a virtualenv/pip environment. For notebooks with executable code, see the
examples. This walk-through can be run from a notebook or interactive python session.
Installation
If you are using Anaconda or Miniconda, install Intake with the following commands:
conda install -c conda-forge intake
If you are using virtualenv/pip, run the following command:
pip install intake
Note that this will install with the minimum of optional requirements. If you want a more
complete install, use intake[complete] instead.
Creating Sample Data
Let's begin by creating a sample data set and catalog. At the command line, run the
intake example command. This will create an example data Catalog and two CSV data files.
These files contains some basic facts about the 50 US states, and the catalog includes a
specification of how to load them.
Loading a Data Source
Data sources can be created directly with the open_*() functions in the intake module. To
read our example data:
>>> import intake
>>> ds = intake.open_csv('states_*.csv')
>>> print(ds)
<intake.source.csv.CSVSource object at 0x1163882e8>
Each open function has different arguments, specific for the data format or service being
used.
Reading Data
Intake reads data into memory using containers you are already familiar with:
• Tables: Pandas DataFrames
• Multidimensional arrays: NumPy arrays
• Semistructured data: Python lists of objects (usually dictionaries)
To find out what kind of container a data source will produce, inspect the container
attribute:
>>> ds.container
'dataframe'
The result will be dataframe, ndarray, or python. (New container types will be added in
the future.)
For data that fits in memory, you can ask Intake to load it directly:
>>> df = ds.read()
>>> df.head()
state slug code nickname ...
0 Alabama alabama AL Yellowhammer State
1 Alaska alaska AK The Last Frontier
2 Arizona arizona AZ The Grand Canyon State
3 Arkansas arkansas AR The Natural State
4 California california CA Golden State
Many data sources will also have quick-look plotting available. The attribute .plot will
list a number of built-in plotting methods, such as .scatter(), see plotting.
Intake data sources can have partitions. A partition refers to a contiguous chunk of data
that can be loaded independent of any other partition. The partitioning scheme is
entirely up to the plugin author. In the case of the CSV plugin, each .csv file is a
partition.
To read data from a data source one chunk at a time, the read_chunked() method returns an
iterator:
>>> for chunk in ds.read_chunked(): print('Chunk: %d' % len(chunk))
...
Chunk: 24
Chunk: 26
Working with Dask
Working with large datasets is much easier with a parallel, out-of-core computing library
like Dask. Intake can create Dask containers (like dask.dataframe) from data sources that
will load their data only when required:
>>> ddf = ds.to_dask()
>>> ddf
Dask DataFrame Structure:
admission_date admission_number capital_city capital_url code constitution_url facebook_url landscape_background_url map_image_url nickname population population_rank skyline_background_url slug state state_flag_url state_seal_url twitter_url website
npartitions=2
object int64 object object object object object object object object int64 int64 object object object object object object object
... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...
... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...
Dask Name: from-delayed, 4 tasks
The Dask containers will be partitioned in the same way as the Intake data source,
allowing different chunks to be processed in parallel. Please read the Dask documentation
to understand the differences when working with Dask collections (Bag, Array or
Data-frames).
Opening a Catalog
A Catalog is a collection of data sources, with the type and arguments prescribed for
each, and arbitrary metadata about each source. In the simplest case, a catalog can be
described by a file in YAML format, a "Catalog file". In real usage, catalogues can be
defined in a number of ways, such as remote files, by connecting to a third-party data
service (e.g., SQL server) or through an Intake Server protocol, which can implement any
number of ways to search and deliver data sources.
The intake example command, above, created a catalog file with the following YAML-syntax
content:
sources:
states
description: US state information from [CivilServices](https://civil.services/)
driver: csv
args:
urlpath: '{{ CATALOG_DIR }}/states_*.csv'
metadata:
origin_url: 'https://github.com/CivilServiceUSA/us-states/blob/v1.0.0/data/states.csv'
To load a Catalog from a Catalog file:
>>> cat = intake.open_catalog('us_states.yml')
>>> list(cat)
['states']
This catalog contains one data source, called states. It can be accessed by attribute:
>>> cat.states.to_dask()[['state','slug']].head()
state slug
0 Alabama alabama
1 Alaska alaska
2 Arizona arizona
3 Arkansas arkansas
4 California california
Placing data source specifications into a catalog like this enables declaring data sets in
a single canonical place, and not having to use boilerplate code in each notebook/script
that makes use of the data. The catalogs can also reference one-another, be stored
remotely, and include extra metadata such as a set of named quick-look plots that are
appropriate for the particular data source. Note that catalogs are not restricted to being
stored in YAML files, that just happens to be the simplest way to display them.
Many catalog entries will also contain "user_parameter" blocks, which are indications of
options explicitly allowed by the catalog author, or for validation or the values passed.
The user can customise how a data source is accessed by providing values for the
user_parameters, overriding the arguments specified in the entry, or passing extra keyword
arguments to be passed to the driver. The keywords that should be passed are limited to
the user_parameters defined and the inputs expected by the specific driver - such usage is
expected only from those already familiar with the specifics of the given format. In the
following example, the user overrides the "csv_kwargs" keyword, which is described in the
documentation for CSVSource and gets passed down to the CSV reader:
# pass extra kwargs understood by the csv driver
>>> intake.cat.states(csv_kwargs={'header': None, 'skiprows': 1}).read().head()
0 1 ... 17
0 Alabama alabama ... https://twitter.com/alabamagov
1 Alaska alaska ... https://twitter.com/alaska
Note that, if you are creating such catalogs, you may well start by trying the open_csv
command, above, and then use print(ds.yaml()). If you do this now, you will see that the
output is very similar to the catalog file we have provided.
Installing Data Source Packages
Intake makes it possible to create Data packages (pip or conda) that install data sources
into a global catalog. For example, we can install a data package containing the same
data we have been working with:
conda install -c intake data-us-states
Conda installs the catalog file in this package to
$CONDA_PREFIX/share/intake/us_states.yml. Now, when we import intake, we will see the
data from this package appear as part of a global catalog called intake.cat. In this
particular case we use Dask to do the reading (which can handle larger-than-memory data
and parallel processing), but read() would work also:
>>> import intake
>>> intake.cat.states.to_dask()[['state','slug']].head()
state slug
0 Alabama alabama
1 Alaska alaska
2 Arizona arizona
3 Arkansas arkansas
4 California california
The global catalog is a union of all catalogs installed in the conda/virtualenv
environment and also any catalogs installed in user-specific locations.
Adding Data Source Packages using the Intake path
Intake checks the Intake config file for catalog_path or the environment variable
"INTAKE_PATH" for a colon separated list of paths (semicolon on windows) to search for
catalog files. When you import intake we will see all entries from all of the catalogues
referenced as part of a global catalog called intake.cat.
Using the GUI
A graphical data browser is available in the Jupyter notebook environment or standalone
web-server. It will show the contents of any installed catalogs, plus allows for
selecting local and remote catalogs, to browse and select entries from these. See gui.
Use Cases - I want to...
Here follows a list of specific things that people may want to get done, and details of
how Intake can help. The details of how to achieve each of these activities can be found
in the rest of the detailed documentation.
Avoid copy&paste of blocks of code for accessing data
This is a very common pattern, if you want to load some specific data, to find someone,
perhaps a colleague, who has accessed it before, and copy that code. Such a practice is
extremely error prone, and cause a proliferation of copies of code, which may evolve over
time, with various versions simultaneously in use.
Intake separates the concerns of data-source specification from code. The specs are stored
separately, and all users can reference the one and only authoritative definition, whether
in a shared file, a service visible to everyone or by using the Intake server. This spec
can be updated so that everyone gets the current version instead of relying on outdated
code.
Version control data sources
Version control (e.g., using git) is an essential practice in modern software engineering
and data science. It ensures that the change history is recorded, with times, descriptions
and authors along with the changes themselves.
When data is specified using a well-structured syntax such as YAML, it can be checked into
a version controlled repository in the usual fashion. Thus, you can bring rigorous
practices to your data as well as your code.
If using conda packages to distribute data specifications, these come with a natural
internal version numbering system, such that users need only do conda update ... to get
the latest version.
Install data
Often, finding and grabbing data is a major hurdle to productivity. People may be required
to download artifacts from various places or search through storage systems to find the
specific thing that they are after. One-line commands which can retrieve data-source
specifications or the files themselves can be a massive time-saver. Furthermore, each
data-set will typically need its own code to be able to access it, and probably additional
software dependencies.
Intake allows you to build conda packages, which can include catalog files referencing
online resources, or to include data files directly in that package. Whether uploaded to
anaconda.org or hosted on a private enterprise channel, getting the data becomes a single
conda install ... command, whereafter it will appear as an entry in intake.cat. The conda
package brings versioning and dependency declaration for free, and you can include any
code that may be required for that specific data-set directly in the package too.
Update data specifications in-place
Individual data-sets often may be static, but commonly, the "best" data to get a job done
changes with time as new facts emerge. Conversely, the very same data might be better
stored in a different format which is, for instance, better-suited to parallel access in
the cloud. In such situations, you really don't want to force all the data scientists who
rely on it to have their code temporarily broken and be forced to change this code.
By working with a catalog file/service in a fixed shared location, it is possible to
update the data source specs in-place. When users now run their code, they will get the
latest version. Because all Intake drivers have the same API, the code using the data will
be identical and not need to be changed, even when the format has been updated to
something more optimised.
Access data stored on cloud resources
Services such as AWS S3, GCS and Azure Datalake (or private enterprise variants of these)
are increasingly popular locations to amass large amounts of data. Not only are they
relatively cheap per GB, but they provide long-term resilience, metadata services, complex
access control patterns and can have very large data throughput when accessed in parallel
by machines on the same architecture.
Intake comes with integration to cloud-based storage out-of-the box for most of the
file-based data formats, to be able to access the data directly in-place and in parallel.
For the few remaining cases where direct access is not feasible, the caching system in
Intake allows for download of files on first use, so that all further access is much
faster.
Work with Big Data
The era of Big Data is here! The term means different things to different people, but
certainly implies that an individual data-set is too large to fit into the memory of a
typical workstation computer (>>10GB). Nevertheless, most data-loading examples available
use functions in packages such as pandas and expect to be able to produce in-memory
representations of the whole data. This is clearly a problem, and a more general answer
should be available aside from "get more memory in your machine".
Intake integrates with Dask and Spark, which both offer out-of-core computation (loading
the data in chunks which fit in memory and aggregating result) or can spread their work
over a cluster of machines, effectively making use of the shared memory resources of the
whole cluster. Dask integration is built into the majority of the the drivers and exposed
with the .to_dask() method, and Spark integration is available for a small number of
drivers with a similar .to_spark() method, as well as directly with the intake-spark
package.
Intake also integrates with many data services which themselves can perform big-data
computations, only extracting the smaller aggregated data-sets that do fit into memory for
further analysis. Services such as SQL systems, solr, elastic-search, splunk, accumulo and
hbase all can distribute the work required to fulfill a query across many nodes of a
cluster.
Find the right data-set
Browsing for the data-set which will solve a particular problem can be hard, even when the
data have been curated and stored in a single, well-structured system. You do not want to
rely on word-of-mouth to specify which data is right for which job.
Intake catalogs allow for self-description of data-sets, with simple text and arbitrary
metadata, with a consistent access pattern. Not only can you list the data available to
you, but you can find out what exactly that data represents, and the form the data would
take if loaded (table versus list of items, for example). This extra metadata is also
searchable: you can descend through a hierarchy of catalogs with a single search, and find
all the entries containing some particular keywords.
You can use the Intake GUI to graphically browse through your available data-sets or point
to catalogs available to you, look through the entries listed there and get information
about each, or even show a sample of the data or quick-look plots. The GUI is also able to
execute searches and browse file-systems to find data artifacts of interest. This same
functionality is also available via a command-line interface or programmatically.
Work remotely
Interacting with cloud storage resources is very convenient, but you will not want to
download large amounts of data to your laptop or workstation for analysis. Intake finds
itself at home in the remote-execution world of jupyter and Anaconda Enterprise and other
in-browser technologies. For instance, you can run the Intake GUI either as a stand-alone
application for browsing data-sets or in a notebook for full analytics, and have all the
runtime live on a remote machine, or perhaps a cluster which is co-located with the data
storage. Together with cloud-optimised data formats such as parquet, this is an ideal
set-up for processing data at web scale.
Transform data to efficient formats for sharing
A massive amount of data exists in human-readable formats such as JSON, XML and CSV, which
are not very efficient in terms of space usage and need to be parsed on load to turn into
arrays or tables. Much faster processing times can be had with modern compact, optimised
formats, such as parquet.
Intake has a "persist" mechanism to transform any input data-source into the format most
appropriate for that type of data, e.g., parquet for tabular data. The persisted data will
be used in preference at analysis time, and the schedule for updating from the original
source is configurable. The location of these persisted data-sets can be shared with
others, so they can also gain the benefits, or the "export" variant can be used to produce
an independent version in the same format, together with a spec to reference it by; you
would then share this spec with others.
Access data without leaking credentials
Security is important. Users' identity and authority to view specific data should be
established before handing over any sensitive bytes. It is, unfortunately, all too common
for data scientists to include their username, passwords or other credentials directly in
code, so that it can run automatically, thus presenting a potential security gap.
Intake does not manage credentials or user identities directly, but does provide hooks for
fetching details from the environment or other service, and using the values in templating
at the time of reading the data. Thus, the details are not included in the code, but every
access still requires for them to be present.
In other cases, you may want to require the user to provide their credentials every time,
rather that automatically establish them, and "user parameters" can be specified in Intake
to cover this case.
Establish a data gateway
The Intake server protocol allows you fine-grained control over the set of data sources
that are listed, and exactly what to return to a user when they want to read some of that
data. This is an ideal opportunity to include authorisation checks, audit logging, and any
more complicated access patterns, as required.
By streaming the data through a single channel on the server, rather than allowing users
direct access to the data storage backend, you can log and verify all access to your data.
Clear distinction between data curator and analyst roles
It is desirable to separate out two tasks: the definition of data-source specifications,
and accessing and using data. This is so that those who understand the origins of the data
and the implications of various formats and other storage options (such as chunk-size)
should make those decisions and encode what they have done into specs. It leaves the data
users, e.g., data scientists, free to find and use the data-sets appropriate for their
work and simply get on with their job - without having to learn about various storage
formats and access APIs.
This separation is at the very core of what Intake was designed to do.
Users to be able to access data without learning every backend API
Data formats and services are a wide mess of many libraries and APIs. A large amount of
time can be wasted in the life of a data scientist or engineer in finding out the details
of the ones required by their work. Intake wraps these various libraries, REST APIs and
similar, to provide a consistent experience for the data user. source.read() will simply
get all of the data into memory in the container type for that source - no further
parameters or knowledge required.
Even for the curator of data catalogs or data driver authors, the framework established by
Intake provides a lot of convenience and simplification which allows each person to deal
with only the specifics of their job.
Data sources to be self-describing
Having a bunch of files in some directory is a very common pattern for data storage in the
wild. There may or may not be a README file co-located giving some information in a
human-readable form, but generally not structured - such files are usually different in
every case.
When a data source is encoded into a catalog, the spec offers a natural place to describe
what that data is, along with the possibility to provide an arbitrary amount of structured
metadata and to describe any parameters that are to be exposed for user choice.
Furthermore, Intake data sources each have a particular container type, so that users know
whether to expect a dataframe, array, etc., and simple introspection methods like describe
and discover which return basic information about the data without having to load all of
it into memory first.
A data source hierarchy for natural structuring
Usually, the set of data sources held by an organisation have relationships to one
another, and would be poorly served to be provided as a simple flat list of everything
available. Intake allows catalogs to refer to other catalogs. This means, that you can
group data sources by various facets (type, department, time...) and establish
hierarchical data-source trees within which to find the particular data most likely to be
of interest. Since the catalogs live outside and separate from the data files themselves,
as many hierarchy structures as thought useful could be created.
For even more complicated data source meta-structures, it is possible to store all the
details and even metadata in some external service (e.g., traditional SQL tables) with
which Intake can interact to perform queries and return particular subsets of the
available data sources.
Expose several data collections under a single system
There are already several catalog-like data services in existence in the world, and some
organisation may have several of these in-house for various different purposes. For
example, an SQL server may hold details of customer lists and transactions, but historical
time-series and reference data may be held separately in archival data formats like
parquet on a file-storage system; while real-time system monitoring is done by a totally
unrelated system such as Splunk or elastic search.
Of course, Intake can read from various file formats and data services. However, it can
also interpret the internal conception of data catalogs that some data services may have.
For example, all of the tables known to the SQL server, or all of the pre-defined queries
in Splunk can be automatically included as catalogs in Intake, and take their place
amongst the regular YAML-specified data sources, with exactly the same usage for all of
them.
These data sources and their hierarchical structure can then be exposed via the graphical
data browser, for searching, selecting and visualising data-sets.
Modern visualisations for all data-sets
Intake is integrated with the comprehensive holoviz suite, particularly hvplot, to bring
simple yet powerful data visualisations to any Intake data source by using just one single
method for everything. These plots are interactive, and can include server-side dynamic
aggregation of very large data-sets to display more data points than the browser can
handle.
You can specify specific plot types right in the data source definition, to have these
customised visualisations available to the user as simple one-liners known to reveal the
content of the data, or even view the same visuals right in the graphical data source
browser application. Thus, Intake is already an all-in-one data investigation and
dashboarding app.
Update data specifications in real time
Intake data catalogs are not limited to reading static specification from files. They can
also execute queries on remote data services and return lists of data sources dynamically
at runtime. New data sources may appear, for example, as directories of data files are
pushed to a storage service, or new tables are created within a SQL server.
Distribute data in a custom format
Sometimes, the well-known data formats are just not right for a given data-set, and a
custom-built format is required. In such cases, the code to read the data may not exist in
any library. Intake allows for code to be distributed along with data source
specs/catalogs or even files in a single conda package. That encapsulates everything
needed to describe and use that particular data, and can then be distributed as a single
entity, and installed with a one-liner.
Furthermore, should the few builtin container types (sequence, array, dataframe) not be
sufficient, you can supply your own, and then build drivers that use it. This was done,
for example, for xarray-type data, where multiple related N-D arrays share a coordinate
system and metadata. By creating this container, a whole world of scientific and
engineering data was opened up to Intake. Creating new containers is not hard, though, and
we foresee more coming, such as machine-learning models and streaming/real-time data.
Create Intake data-sets from scratch
If you have a set of files or a data service which you wish to make into a data-set, so
that you can include it in a catalog, you should use the set of functions intake.open_*,
where you need to pick the function appropriate for your particular data. You can use
tab-completion to list the set of data drivers you have installed, and find others you may
not yet have installed at plugin-directory. Once you have determined the right set of
parameters to load the data in the manner you wish, you can use the source's .yaml()
method to find the spec that describes the source, so you can insert it into a catalog
(with appropriate description and metadata). Alternatively, you can open a YAML file as a
catalog with intake.open_catalog and use its .add() method to insert the source into the
corresponding file.
If, instead, you have data in your session in one of the containers supported by Intake
(e.g., array, data-frame), you can use the intake.upload() function to save it to files in
an appropriate format and a location you specify, and give you back a data-source
instance, which, again, you can use with .yaml() or .add(), as above.
Overview
Introduction
This page describes the technical design of Intake, with brief details of the aims of the
project and components of the library
Why Intake?
Intake solves a related set of problems:
• Python API standards for loading data (such as DB-API 2.0) are optimized for
transactional databases and query results that are processed one row at a time.
• Libraries that do load data in bulk tend to each have their own API for doing so, which
adds friction when switching data formats.
• Loading data into a distributed data structure (like those found in Dask and Spark)
often requires writing a separate loader.
• Abstractions often focus on just one data model (tabular, n-dimensional array, or
semi-structured), when many projects need to work with multiple kinds of data.
Intake has the explicit goal of not defining a computational expression system. Intake
plugins load the data into containers (e.g., arrays or data-frames) that provide their
data processing features. As a result, it is very easy to make a new Intake plugin with a
relatively small amount of Python.
Structure
Intake is a Python library for accessing data in a simple and uniform way. It consists of
three parts:
1. A lightweight plugin system for adding data loader drivers for new file formats and
servers (like databases, REST endpoints or other cataloging services)
2. A cataloging system for specifying these sources in simple YAML syntax, or with plugins
that read source specs from some external data service
3. A server-client architecture that can share data catalog metadata over the network, or
even stream the data directly to clients if needed
Intake supports loading data into standard Python containers. The list can be easily
extended, but the currently supported list is:
• Pandas Dataframes - tabular data
• NumPy Arrays - tensor data
• Python lists of dictionaries - semi-structured data
Additionally, Intake can load data into distributed data structures. Currently it
supports Dask, a flexible parallel computing library with distributed containers like
dask.dataframe, dask.array, and dask.bag. In the future, other distributed computing
systems could use Intake to create similar data structures.
Concepts
Intake is built out of four core concepts:
• Data Source classes: the "driver" plugins that each implement loading of some specific
type of data into python, with plugin-specific arguments.
• Data Source: An object that represents a reference to a data source. Data source
instances have methods for loading the data into standard containers, like Pandas
DataFrames, but do not load any data until specifically requested.
• Catalog: A collection of catalog entries, each of which defines a Data Source. Catalog
objects can be created from local YAML definitions, by connecting to remote servers, or
by some driver that knows how to query an external data service.
• Catalog Entry: A named data source held internally by catalog objects, which generate
data source instances when accessed. The catalog entry includes metadata about the
source, as well as the name of the driver and arguments. Arguments can be parameterized,
allowing one entry to return different subsets of data depending on the user request.
The business of a plugin is to go from some data format (bunch of files or some remote
service) to a "Container" of the data (e.g., data-frame), a thing on which you can perform
further analysis. Drivers can be used directly by the user, or indirectly through data
catalogs. Data sources can be pickled, sent over the network to other hosts, and reopened
(assuming the remote system has access to the required files or servers).
See also the glossary.
Future Directions
Ongoing work for enhancements, as well as requests for plugins, etc., can be found at the
issue tracker. See the roadmap for general mid- and long-term goals.
Examples
Here we list links to notebooks and other code demonstrating the use of Intake in various
scenarios. The first section is of general interest to various users, and the sections
that follow tend to be more specific about particular features and workflows.
Many of the entries here include a link to Binder, which a service that lest you execute
code live in a notebook environment. This is a great way to experience using Intake. It
can take a while, sometimes, for Binder to come up; please have patience.
See also the examples repository, containing data-sets which can be built and installed as
conda packages.
General
• Basic Data scientist workflow: using Intake [Static] [Executable].
• Workflow for creating catalogs: a Data Engineer's approach to Intake [Static] [‐
Executable]
Developer
Tutorials delving deeper into the Internals of Intake, for those who wish to contribute
• How you would go about writing a new plugin [Static] [Executable]
Features
More specific examples of Intake functionality
• Caching:
• New-style data package creation [Static]
• Using automatically cached data-files [Static] [Executable]
• Earth science demonstration of cached dataset [Static] [Executable]
• File-name pattern parsing:
• Satellite imagery, science workflow [Static] [Executable]
• How to set up pattern parsing [Static] [Executable]
• Custom catalogs:
• A custom intake plugin that adapts DCAT catalogs [Static] [Executable]
Data
• Anaconda package data, originally announced in this blog
• Planet Four Catalog, originally from https://www.planetfour.org/results
• The official Intake examples
Blogs
These are Intake-related articles that may be of interest.
• Discovering and Exploring Data in a Graphical Interface
• Taking the Pain out of Data Access
• Caching Data on First Read Makes Future Analysis Faster
• Parsing Data from Filenames and Paths
• Intake for cataloguing Spark
• Intake released on Conda-Forge
Talks
• __init__ podcast interview (May 2019)
• AnacondaCon (March 2019)
• PyData DC (November 2018)
• PyData NYC (October 2018)
• ESIP tech dive (November 2018)
News
• See out Wiki page
Deployment Scenarios
In the following sections, we will describe some of the ways in which Intake is used in
real production systems. These go well beyond the typical YAML files presented in the
quickstart and examples sections, which are necessarily short and simple, and do not
demonstrate the full power of Intake.
Sharing YAML files
This is the simplest scenario, and amply described in these documents. The primary
advantage is simplicity: it is enough to put a file in an accessible place (even a gist or
repo), in order for someone else to be able to discover and load that data. Furthermore,
such files can easily refer to one-another, to build up a full tree of data assets with
minimum pain Since YAML files are text, this also lends itself to working well with
version control systems. Furthermore, all sources can describe themselves as YAML, and
the export and upload commands can produce an efficient format (possibly remote) together
with YAML definition in a single step.
Pangeo
The Pangeo collaboration uses Intake to catalog their data holdings, which are generally
in various forms of netCDF-compliant formats, massive multi-dimensional arrays with data
relating to earth and climate science and meteorology. On their cloud-based platform,
containers start up jupyter-lab sessions which have Intake installed, and therefore can
simply pick and load the data that each researcher needs - often requiring large Dask
clusters to actually do the processing.
A static rendering of the catalog contents is available, so that users can browse the
holdings without even starting a python session. This rendering is produced by CI on the
repo whenever new definitions are added, and it also checks (using Intake) that each
definition is indeed loadable.
Pangeo also developed intake-stac, which can talk to STAC servers to make real-time
queries and parse the results into Intake data sources. This is a standard for
spaceo-temporal data assets, and indexes massive amounts of cloud-stored data.
Anaconda Enterprise
Intake will be the basis of the data access and cataloging service within Anaconda
Enterprise, running as a micro-service in a container, and offering data source
definitions to users. The access control, who gets to see which data-set, and serving of
credentials to be able to read from the various data storage services, will all be handled
by the platform and be fully configurable by admins.
National Center for Atmospheric Research
NCAR has developed intake-esm, a mechanism for creating file-based Intake catalogs for
climate data from project efforts such as the Coupled Model Intercomparison Project (CMIP)
and the Community Earth System Model (CESM) Large Ensemble Project. These projects
produce a huge of amount climate data persisted on tape, disk storage components across
multiple (of the order ~300,000) netCDF files. Finding, investigating, loading these files
into data array containers such as xarray can be a daunting task due to the large number
of files a user may be interested in. Intake-esm addresses this issue in three steps:
• Datasets Collection Curation in form of YAML files. These YAML files provide information
about data locations, access pattern, directory structure, etc. intake-esm uses these
YAML files in conjunction with file name templates to construct a local database. Each
row in this database consists of a set of metadata such as experiment, modeling realm,
frequency corresponding to data contained in one netCDF file.
col = intake.open_esm_metadatastore(collection_input_definition="GLADE-CMIP5")
• Search and Discovery: once the database is built, intake-esm can be used for searching
and discovering of climate datasets by eliminating the need for the user to know
specific locations (file path) of their data set of interest:
cat = col.search(variable=['hfls'], frequency='mon', modeling_realm='atmos', institute=['CCCma', 'CNRM-CERFACS'])
• Access: when the user is satisfied with the results of their query, they can ask
intake-esm to load the actual netCDF files into xarray datasets:
dsets = cat.to_xarray(decode_times=True, chunks={'time': 50})
Brookhaven Archive
The Bluesky project uses Intake to dynamically query a MongoDB instance, which holds the
details of experimental and simulation data collections, to return a custom Catalog for
every query. Data-sets can then be loaded into python, or the original raw data can be
accessed ...
Zillow
Zillow is developing Intake to meet the needs of their datalake access layer (DAL), to
encapsulate the highly hierarchical nature of their data. Of particular importance, is the
ability to provide different version (testing/production, and different storage formats)
of the same logical dataset, depending on whether it is being read on a laptop versus the
production infrastructure ...
Intake Server
The server protocol (see server) is simple enough that anyone can write their own
implementation with full customisation and behaviour. In particular, auth and monitoring
would be essential for a production-grade deployment.
USER GUIDE
More detailed information about specific parts of Intake, such as how to author catalogs,
how to use the graphical interface, plotting, etc.
GUI
Using the GUI
Note: the GUI requires panel and bokeh to be available in the current environment.
The Intake top-level singleton intake.gui gives access to a graphical data browser within
the Jupyter notebook. To expose it, simply enter it into a code cell (Jupyter
automatically display the last object in a code cell). [image]
New instances of the GUI are also available by instantiating intake.interface.gui.GUI,
where you can specify a list of catalogs to initially include.
The GUI contains three main areas:
• a list of catalogs. The "builtin" catalog, displayed by default, includes data-sets
installed in the system, the same as intake.cat.
• a list of sources within the currently selected catalog.
• a description of the currently selected source.
Catalogs
Selecting a catalog from the list will display nested catalogs below the parent and
display source entries from the catalog in the list of sources.
Below the lists of catalogs is a row of buttons that are used for adding, removing and
searching-within catalogs:
• Add: opens a sub-panel for adding catalogs to the interface, by either browsing for a
local YAML file or by entering a URL for a catalog, which can be a remote file or Intake
server
• Remove: deletes the currently selected catalog from the list
• Search: opens a sub-panel for finding entries in the currently selected catalog (and its
sub-catalogs)
Add Catalogs
The Add button (+) exposes a sub-panel with two main ways to add catalogs to the
interface: [image]
This panel has a tab to load files from local; from that you can navigate around the
filesystem using the arrow or by editing the path directly. Use the home button to get
back to the starting place. Select the catalog file you need. Use the "Add Catalog" button
to add the catalog to the list above. [image]
Another tab loads a catalog from remote. Any URL is valid here, including cloud locations,
"gcs://bucket/...", and intake servers, "intake://server:port". Without a protocol
specifier, this can be a local path. Again, use the "Add Catalog" button to add the
catalog to the list above. [image]
Finally, you can add catalogs to the interface in code, using the .add() method, which can
take filenames, remote URLs or existing Catalog instances.
Remove Catalogs
The Remove button (-) deletes the currently selected catalog from the list. It is
important to note that this action does not have any impact on files, it only affects what
shows up in the list. [image]
Search
The sub-panel opened by the Search button (🔍) allows the user to search within the
selected catalog [image]
From the Search sub-panel the user enters for free-form text. Since some catalogs contain
nested sub-catalogs, the Depth selector allows the search to be limited to the stated
number of nesting levels. This may be necessary, since, in theory, catalogs can contain
circular references, and therefore allow for infinite recursion. [image]
Upon execution of the search, the currently selected catalog will be searched. Entries
will be considered to match if any of the entered words is found in the description of the
entry (this is case-insensitive). If any matches are found, a new entry will be made in
the catalog list, with the suffix "_search". [image]
Sources
Selecting a source from the list updates the description text on the left-side of the gui.
Below the list of sources is a row of buttons for inspecting the selected data source:
• Plot: opens a sub-panel for viewing the pre-defined (specified in the yaml) plots for
the selected source.
Plot
The Plot button (📊) opens a sub-panel with an area for viewing pre-defined plots.
[image]
These plots are specified in the catalog yaml and that yaml can be displayed by checking
the box next to "show yaml". [image]
The holoviews object can be retrieved from the gui using
intake.interface.source.plot.pane.object, and you can then use it in Python or export it
to a file.
Interactive Visualization
If you have installed the optional extra packages dfviz and xrviz, you can interactively
plot your dataframe or array data, respectively. [image]
The button "customize" will be available for data sources of the appropriate type. Click
this to open the interactive interface. If you have not selected a predefined plot (or
there are none), then the interface will start without any prefilled values, but if you do
first select a plot, then the interface will have its options pre-filled from the options
For specific instructions on how to use the interfaces (which can also be used
independently of the Intake GUI), please navigate to the linked documentation.
Note that the final parameters that are sent to hvPlot to produce the output each time a
plot if updated, are explicitly available in YAML format, so that you can save the state
as a "predefined plot" in the catalog. The same set of parameters can also be used in
code, with datasource.plot(...). [image]
Using the Selection
Once catalogs are loaded and the desired sources has been identified and selected, the
selected sources will be available at the .sources attribute (intake.gui.sources). Each
source entry has informational methods available and can be opened as a data source, as
with any catalog entry:
In [ ]: source_entry = intake.gui.sources[0]
source_entry
Out :
name: sea_ice_origin
container: dataframe
plugin: ['csv']
description: Arctic/Antarctic Sea Ice
direct_access: forbid
user_parameters: []
metadata:
args:
urlpath: https://timeseries.weebly.com/uploads/2/1/0/8/21086414/sea_ice.csv
In [ ]: data_source = source_entry() # may specify parameters here
data_source.read()
Out : < some data >
In [ ]: source_entry.plot() # or skip data source step
Out : < graphics>
Catalogs
Data catalogs provide an abstraction that allows you to externally define, and optionally
share, descriptions of datasets, called catalog entries. A catalog entry for a dataset
includes information like:
• The name of the Intake driver that can load the data
• Arguments to the __init__() method of the driver
• Metadata provided by the catalog author (such as field descriptions and types, or data
provenance)
In addition, Intake allows the arguments to data sources to be templated, with the
variables explicitly expressed as "user parameters". The given arguments are rendered
using jinja2, the values of named user parameterss, and any overrides. The parameters are
also offer validation of the allowed types and values, for both the template values and
the final arguments passed to the data source. The parameters are named and described, to
indicate to the user what they are for. This kind of structure can be used to, for
example, choose between two parts of a given data source, like "latest" and "stable", see
the entry1_part entry in the example below.
The user of the catalog can always override any template or argument value at the time
that they access a give source.
The Catalog class
In Intake, a Catalog instance is an object with one or more named entries. The entries
might be read from a static file (e.g., YAML, see the next section), from an Intake server
or from any other data service that has a driver. Drivers which create catalogs are
ordinary DataSource classes, except that they have the container type "catalog", and do
not return data products via the read() method.
For example, you might choose to instantiate the base class and fill in some entries
explicitly in your code
from intake.catalog import Catalog
from intake.catalog.local import LocalCatalogEntry
mycat = Catalog.from_dict({
'source1': LocalCatalogEntry(name, description, driver, args=...),
...
})
Alternatively, subclasses of Catalog can define how entries are created from whichever
file format or service they interact with, examples including RemoteCatalog and
SQLCatalog. These generate entries based on their respective targets; some provide
advanced search capabilities executed on the server.
YAML Format
Intake catalogs can most simply be described with YAML files. This is very common in the
tutorials and this documentation, because it simple to understand, but demonstrate the
many features of Intake. Note that YAML files are also the easiest way to share a catalog,
simply by copying to a publicly-available location such as a cloud storage bucket. Here
is an example:
metadata:
version: 1
parameters:
file_name:
type: str
description: default file name for child entries
default: example_file_name
sources:
example:
description: test
driver: random
args: {}
entry1_full:
description: entry1 full
metadata:
foo: 'bar'
bar: [1, 2, 3]
driver: csv
args: # passed to the open() method
urlpath: '{{ CATALOG_DIR }}/entry1_*.csv'
entry1_part:
description: entry1 part
parameters: # User parameters
part:
description: section of the data
type: str
default: "stable"
allowed: ["latest", "stable"]
driver: csv
args:
urlpath: '{{ CATALOG_DIR }}/entry1_{{ part }}.csv'
entry2:
description: entry2
driver: csv
args:
# file_name parameter will be inherited from file-level parameters, so will
# default to "example_file_name"
urlpath: '{{ CATALOG_DIR }}/entry2/{{ file_name }}.csv`
Metadata
Arbitrary extra descriptive information can go into the metadata section. Some fields will
be claimed for internal use and some fields may be restricted to local reading; but for
now the only field that is expected is version, which will be updated when a breaking
change is made to the file format. Any catalog will have .metadata and .version attributes
available.
Note that each source also has its own metadata.
The metadata section an also contain parameters which will be inherited by the sources in
the file (note that these sources can augment these parameters, or override them with
their own parameters).
Extra drivers
The driver: entry of a data source specification can be a driver name, as has been shown
in the examples so far. It can also be an absolute class path to use for the data source,
in which case there will be no ambiguity about how to load the data. That is the the
preferred way to be explicit, when the driver name alone is not enough (see Driver
Selection, below).
plugins:
source:
- module: intake.catalog.tests.example1_source
sources:
...
However, you do not, in general, need to do this, since the driver: field of each source
can also explicitly refer to the plugin class.
Sources
The majority of a catalog file is composed of data sources, which are named data sets that
can be loaded for the user. Catalog authors describe the contents of data set, how to
load it, and optionally offer some customization of the returned data. Each data source
has several attributes:
• name: The canonical name of the source. Best practice is to compose source names from
valid Python identifiers. This allows Intake to support things like tab completion of
data source names on catalog objects. For example, monthly_downloads is a good source
name.
• description: Human readable description of the source. To help catalog browsing tools,
the description should be Markdown.
• driver: Name of the Intake Driver to use with this source. Must either already be
installed in the current Python environment (i.e. with conda or pip) or loaded in the
plugin section of the file. Can be a simple driver name like "csv" or the full path to
the implementation class like "package.module.Class".
• args: Keyword arguments to the init method of the driver. Arguments may use template
expansion.
• metadata: Any metadata keys that should be attached to the data source when opened.
These will be supplemented by additional metadata provided by the driver. Catalog
authors can use whatever key names they would like, with the exception that keys
starting with a leading underscore are reserved for future internal use by Intake.
• direct_access: Control whether the data is directly accessed by the client, or proxied
through a catalog server. See Server Catalogs for more details.
• parameters: A dictionary of data source parameters. See below for more details.
Caching Source Files Locally
This method of defining the cache with a dedicated block is deprecated, see the Remote
Access section, below
To enable caching on the first read of remote data source files, add the cache section
with the following attributes:
• argkey: The args section key which contains the URL(s) of the data to be cached.
• type: One of the keys in the cache registry [intake.source.cache.registry], referring to
an implementation of caching behaviour. The default is "file" for the caching of one or
more files.
Example:
test_cache:
description: cache a csv file from the local filesystem
driver: csv
cache:
- argkey: urlpath
type: file
args:
urlpath: '{{ CATALOG_DIR }}/cache_data/states.csv'
The cache_dir defaults to ~/.intake/cache, and can be specified in the intake
configuration file or INTAKE_CACHE_DIR environment variable, or at runtime using the
"cache_dir" key of the configuration. The special value "catdir" implies that cached
files will appear in the same directory as the catalog file in which the data source is
defined, within a directory named "intake_cache". These will not appear in the cache usage
reported by the CLI.
Optionally, the cache section can have a regex attribute, that modifies the path of the
cache on the disk. By default, the cache path is made by concatenating cache_dir, dataset
name, hash of the url, and the url itself (without the protocol). regex attribute allows
one to remove part of the url (the matching part).
Caching can be disabled at runtime for all sources regardless of the catalog
specification:
from intake.config import conf
conf['cache_disabled'] = True
By default, progress bars are shown during downloads if the package tqdm is available, but
this can be disabled (e.g., for consoles that don't support complex text) with
conf['cache_download_progress'] = False
or, equivalently, the environment parameter INTAKE_CACHE_PROGRESS.
The "types" of caching are that supported are listed in intake.source.cache.registry, see
the docstrings of each for specific parameters that should appear in the cache block.
It is possible to work with compressed source files by setting type: compression in the
cache specification. By default the compression type is inferred from the file extension,
otherwise it can be set by assigning the decomp variable to any of the options listed in
intake.source.decompress.decomp. This will extract all the file(s) in the compressed file
referenced by urlpath and store them in the cache directory.
In cases where miscellaneous files are present in the compressed file, a regex_filter
parameter can be used. Only the extracted filenames that match the pattern will be loaded.
The cache path is appended to the filename so it is necessary to include a wildcard to the
beginning of the pattern.
Example:
test_compressed:
driver: csv
args:
urlpath: 'compressed_file.tar.gz'
cache:
- type: compressed
decomp: tgz
argkey: urlpath
regex_filter: '.*data.csv'
Templating
Intake catalog files support Jinja2 templating for driver arguments. Any occurrence of a
substring like {{field}} will be replaced by the value of the user parameters with that
same name, or the value explicitly provided by the user. For how to specify these user
parameters, see the next section.
Some additional values are available for templating. The following is always available:
CATALOG_DIR, the full path to the directory containing the YAML catalog file. This is
especially useful for constructing paths relative to the catalog directory to locate data
files and custom drivers. For example, the search for CSV files for the two "entry1"
blocks, above, will happen in the same directory as where the catalog file was found.
The following functions may be available. Since these execute code, the user of a catalog
may decide whether they trust those functions or not.
• env("USER"): look in the set environment variables for the named variable
• client_env("USER"): exactly the same, except that when using a client-server topology,
the value will come from the environment of the client.
• shell("get_login thisuser -t"): execute the command, and use the output as the value.
The output will be trimmed of any trailing whitespace.
• client_shell("get_login thisuser -t"): exactly the same, except that when using a
client-server topology, the value will come from the system of the client.
The reason for the "client" versions of the functions is to prevent leakage of potentially
sensitive information between client and server by controlling where lookups happen. When
working without a server, only the ones without "client" are used.
An example:
sources:
personal_source:
description: This source needs your username
args:
url: "http://server:port/user/{{env(USER)}}"
Here, if the user is named "blogs", the url argument will resolve to
"http://server:port/user/blogs"; if the environment variable is not defined, it will
resolve to "http://server:port/user/"
Parameter Definition
Source parameters
A source definition can contain a "parameters" block. Expressed in YAML, a parameter may
look as follows:
parameters:
name:
description: name to use # human-readable text for what this parameter means
type: str # one of bool, str, int, float, list[str | int | float], datetime, mlist
default: normal # optional, value to assume if user does not override
allowed: ["normal", "strange"] # optional, list of values that are OK, for validation
min: "n" # optional, minimum allowed, for validation
max: "t" # optional, maximum allowed, for validation
A parameter, not to be confused with an argument, can have one of two uses:
• to provide values for variables to be used in templating the arguments. If the pattern
"{{name}}" exists in any of the source arguments, it will be replaced by the value of
the parameter. If the user provides a value (e.g., source =
cat.entry(name='something")), that will be used, otherwise the default value. If there
is no user input or default, the empty value appropriate for type is used. The default
field allows for the same function expansion as listed for arguments, above.
• If an argument with the same name as the parameter exists, its value, after any
templating, will be coerced to the given type of the parameter and validated against the
allowed/max/min. It is therefore possible to use the string templating system (e.g., to
get a value from the environment), but pass the final value as, for example, an integer.
It makes no sense to provide a default for this case (the argument already has a value),
but providing a default will not raise an exception.
• the "mlist" type is special: it means that the input must be a list, whose values are
chosen from the allowed list. This is the only type where the parameter value is not the
same type as the allowed list's values, e.g., if a list of str is set for allowed, a
list of str must also be the final value.
Note: the datetime type accepts multiple values: Python datetime, ISO8601 string, Unix
timestamp int, "now" and "today".
Catalog parameters
You can also define user parameters at the catalog level. This applies the parameter to
all entries within that catalog, without having to define it for each and every entry.
Furthermore, catalogs dested within the catalog will also inherit the parameter(s).
For example, with the following spec
metadata:
version: 1
parameters:
bucket:
type: str
description: description
default: test_bucket
sources:
param_source:
driver: parquet
description: description
args:
urlpath: s3://{{bucket}}/file.parquet
subcat:
driver: yaml_file
path: "{{CATALOG_DIR}}/other.yaml"
If cat is the corresponsing catalog instance, the URL of source cat.param_source will
evaluate to "s3://test_bucket/file.parquet" by default, but the parameter can be
overridden with cat.param_source(bucket="other_bucket"). Also, any entries of subcat,
another catalog referenced from here, would also have the "bucket"-named parameter
attached to all sources. Of course, those sources do no need to make use of the parameter.
To change the default, we can gerenate a new instance
cat2 = cat(bucket="production") # sets default value of "bucket" for cat2
subcat = cat.subcat(bucket="production") # sets default only for the nested catalog
Of course, in these situations you can still override the value of the parameter for any
source, or pass explicit values for the arguments of the source, as normal.
For cases where the catalog is not defined in a YAML spec, the argument user_parameters to
the constructor takes the same form as parameters above: a dict of user parameters, either
as UserParameter instances or as a dictionary spec for each one.
Driver Selection
In some cases, it may be possible that multiple backends are capable of loading from the
same data format or service. Sometimes, this may mean two drivers with unique names, or a
single driver with a parameter to choose between the different backends.
However, it is possible that multiple drivers for reading a particular type of data also
share the same driver name: for example, both the intake-iris and the intake-xarray
packages contain drivers with the name "netcdf", which are capable of reading the same
files, but with different backends. Here we will describe the various possibilities of
coping with this situation. Intake's plugin system makes it easy to encode such choices.
It may be acceptable to use any driver which claims to handle that data type, or to give
the option of which driver to use to the user, or it may be necessary to specify which
precise driver(s) are appropriate for that particular data. Intake allows all of these
possibilities, even if the backend drivers require extra arguments.
Specifying a single driver explicitly, rather than using a generic name, would look like
this:
sources:
example:
description: test
driver: package.module.PluginClass
args: {}
It is also possible to describe a list of drivers with the same syntax. The first one
found will be the one used. Note that the class imports will only happen at data source
instantiation, i.e., when the entry is selected from the catalog.
sources:
example:
description: test
driver:
- package.module.PluginClass
- another_package.PluginClass2
args: {}
These alternative plugins can also be given data-source specific names, allowing the user
to choose at load time with driver= as a parameter. Additional arguments may also be
required for each option (which, as usual, may include user parameters); however, the same
global arguments will be passed to all of the drivers listed.
sources:
example:
description: test
driver:
first:
class: package.module.PluginClass
args:
specific_thing: 9
second:
class: another_package.PluginClass2
args: {}
Remote Access
(see also remote_data for the implementation details)
Many drivers support reading directly from remote data sources such as HTTP, S3 or GCS. In
these cases, the path to read from is usually given with a protocol prefix such as gcs://.
Additional dependencies will typically be required (requests, s3fs, gcsfs, etc.), any data
package should specify these. Further parameters may be necessary for communicating with
the storage backend and, by convention, the driver should take a parameter storage_options
containing arguments to pass to the backend. Some remote backends may also make use of
environment variables or config files to determine their default behaviour.
The special template variable "CATALOG_DIR" may be used to construct relative URLs in the
arguments to a source. In such cases, if the filesystem used to load that catalog
contained arguments, then the storage_options of that file system will be extracted and
passed to the source. Therefore, all sources which can accept general URLs (beyond just
local paths) must make sure to accept this argument.
As an example of using storage_options, the following two sources would allow for reading
CSV data from S3 and GCS backends without authentication (anonymous access), respectively
sources:
s3_csv:
driver: csv
description: "Publicly accessible CSV data on S3; requires s3fs"
args:
urlpath: s3://bucket/path/*.csv
storage_options:
anon: true
gcs_csv:
driver: csv
description: "Publicly accessible CSV data on GCS; requires gcsfs"
args:
urlpath: gcs://bucket/path/*.csv
storage_options:
token: "anon"
Caching
URLs interpreted by fsspec offer automatic caching. For example, to enable file-based
caching for the first source above, you can do:
sources:
s3_csv:
driver: csv
description: "Publicly accessible CSV data on S3; requires s3fs"
args:
urlpath: simplecache::s3://bucket/path/*.csv
storage_options:
s3:
anon: true
Here we have added the "simplecache" to the URL (this caching backend does not store any
metadata about the cached file) and specified that the "anon" parameter is meant as an
argument to s3, not to the caching mechanism. As each file in s3 is accessed, it will
first be downloaded and then the local version used instead.
You can tailor how the caching works. In particular the location of the local storage can
be set with the cache_storage parameter (under the "simplecache" group of storage_options,
of course) - otherwise they are stored in a temporary location only for the duration of
the current python session. The cache location is particularly useful in conjunction with
an environment variable, or relative to "{{CATALOG_DIR}}", wherever the catalog was loaded
from.
Please see the fsspec documentation for the full set of cache types and their various
options.
Local Catalogs
A Catalog can be loaded from a YAML file on the local filesystem by creating a Catalog
object:
from intake import open_catalog
cat = open_catalog('catalog.yaml')
Then sources can be listed:
list(cat)
and data sources are loaded via their name:
data = cat.entry_part1
and you can optionally configure new instances of the source to define user parameters or
override arguments by calling either of:
data = cat.entry_part1.configure_new(part='1')
data = cat.entry_part1(part='1') # this is a convenience shorthand
Intake also supports loading a catalog from all of the files ending in .yml and .yaml in a
directory, or by using an explicit glob-string. Note that the URL provided may refer to a
remote storage systems by passing a protocol specifier such as s3://, gcs://.:
cat = open_catalog('/research/my_project/catalog.d/')
Intake Catalog objects will automatically reload changes or new additions to catalog files
and directories on disk. These changes will not affect already-opened data sources.
Catalog Nesting
A catalog is just another type of data source for Intake. For example, you can print a
YAML specification corresponding to a catalog as follows:
cat = intake.open_catalog('cat.yaml')
print(cat.yaml())
results in:
sources:
cat:
args:
path: cat.yaml
description: ''
driver: intake.catalog.local.YAMLFileCatalog
metadata: {}
The point here, is that this can be included in another catalog. (It would, of course, be
better to include a description and the full path of the catalog file here.) If the entry
above were saved to another file, "root.yaml", and the original catalog contained an
entry, data, you could access it as:
root = intake.open_catalog('root.yaml')
root.cat.data
It is, therefore, possible to build up a hierarchy of catalogs referencing each other.
These can, of course, include remote URLs and indeed catalog sources other than simple
files (all the tables on a SQL server, for instance). Plus, since the argument and
parameter system also applies to entries such as the example above, it would be possible
to give the user a runtime choice of multiple catalogs to pick between, or have this
decision depend on an environment variable.
Server Catalogs
Intake also includes a server which can share an Intake catalog over HTTP (or HTTPS with
the help of a TLS-enabled reverse proxy). From the user perspective, remote catalogs
function identically to local catalogs:
cat = open_catalog('intake://catalog1:5000')
list(cat)
The difference is that operations on the catalog translate to requests sent to the catalog
server. Catalog servers provide access to data sources in one of two modes:
• Direct access: In this mode, the catalog server tells the client how to load the data,
but the client uses its local drivers to make the connection. This requires the client
has the required driver already installed and has direct access to the files or data
servers that the driver will connect to.
• Proxied access: In this mode, the catalog server uses its local drivers to open the data
source and stream the data over the network to the client. The client does not need any
special drivers to read the data, and can read data from files and data servers that it
cannot access, as long as the catalog server has the required access.
Whether a particular catalog entry supports direct or proxied access is determined by the
direct_access option:
• forbid (default): Force all clients to proxy data through the catalog server
• allow: If the client has the required driver, access the source directly, otherwise
proxy the data through the catalog server.
• force: Force all clients to access the data directly. If they do not have the required
driver, an exception will be raised.
Note that when the client is loading a data source via direct access, the catalog server
will need to send the driver arguments to the client. Do not include sensitive
credentials in a data source that allows direct access.
Client Authorization Plugins
Intake servers can check if clients are authorized to access the catalog as a whole, or
individual catalog entries. Typically a matched pair of server-side plugin (called an
"auth plugin") and a client-side plugin (called a "client auth plugin) need to be enabled
for authorization checks to work. This feature is still in early development, but see
module intake.auth.secret for a demonstration pair of server and client classes
implementation auth via a shared secret. See auth-plugins.
Command Line Tools
The package installs two executable commands: for starting the catalog server; and a
client for accessing catalogs and manipulating the configuration.
Configuration
A file-based configuration service is available to Intake. This file is by default sought
at the location ~/.intake/conf.yaml, but either of the environment variables
INTAKE_CONF_DIR or INTAKE_CONF_FILE can be used to specify another directory or file. If
both are given, the latter takes priority.
At present, the configuration file might look as follows:
auth:
cls: "intake.auth.base.BaseAuth"
port: 5000
catalog_path:
- /home/myusername/special_dir
These are the defaults, and any parameters not specified will take the values above
• the Intake Server will listen on port 5000 (this can be overridden on the command line,
see below)
• and the auth system used will be the fully qualified class given (which, for BaseAuth,
always allows access). For further information on securing the Intake Server, see the
authplugins.
See intake.config.defaults for a full list of keys and their default values.
Log Level
The logging level is configurable using Python's built-in logging module.
The config option 'logging' holds the current level for the intake logger, and can take
values such as 'INFO' or 'DEBUG'. This can be set in the conf.yaml file of the config
directory (e.g., ~/.intake/), or overridden by the environment variable INTAKE_LOG_LEVEL.
Furthermore, the level and settings of the logger can be changed programmatically in code:
import logging
logger = logging.getLogger('intake')
logger.setLevel(logging.DEBUG)
logget.addHandler(..)
Intake Server
The server takes one or more catalog files as input and makes them available on port 5000
by default.
You can see the full description of the server command with:
>>> intake-server --help
usage: intake-server [-h] [-p PORT] [--list-entries] [--sys-exit-on-sigterm]
[--flatten] [--no-flatten] [-a ADDRESS]
FILE [FILE ...]
Intake Catalog Server
positional arguments:
FILE Name of catalog YAML file
optional arguments:
-h, --help show this help message and exit
-p PORT, --port PORT port number for server to listen on
--list-entries list catalog entries at startup
--sys-exit-on-sigterm
internal flag used during unit testing to ensure
.coverage file is written
--flatten
--no-flatten
-a ADDRESS, --address ADDRESS
address to use as a host, defaults to the address in
the configuration file, if provided otherwise localhost
usage: intake-server [-h] [-p PORT] [--list-entries] [--sys-exit-on-sigterm]
[--flatten] [--no-flatten] [-a ADDRESS]
FILE [FILE ...]
To start the server with a local catalog file, use the following:
>>> intake-server intake/catalog/tests/catalog1.yml
Creating catalog from:
- intake/catalog/tests/catalog1.yml
catalog_args ['intake/catalog/tests/catalog1.yml']
Entries: entry1,entry1_part,use_example1
Listening on port 5000
You can use the catalog client (defined below) using:
$ intake list intake://localhost:5000
entry1
entry1_part
use_example1
Intake Client
While the Intake data sources will typically be accessed through the Python API, you can
use the client to verify a catalog file.
Unlike the server command, the client has several subcommands to access a catalog. You can
see the list of available subcommands with:
>>> intake --help
usage: intake {list,describe,exists,get,discover} ...
We go into further detail in the following sections.
List
This subcommand lists the names of all available catalog entries. This is useful since
other subcommands require these names.
If you wish to see the details about each catalog entry, use the --full flag. This is
equivalent to running the intake describe subcommand for all catalog entries.
>>> intake list --help
usage: intake list [-h] [--full] URI
positional arguments:
URI Catalog URI
optional arguments:
-h, --help show this help message and exit
--full
>>> intake list intake/catalog/tests/catalog1.yml
entry1
entry1_part
use_example1
>>> intake list --full intake/catalog/tests/catalog1.yml
[entry1] container=dataframe
[entry1] description=entry1 full
[entry1] direct_access=forbid
[entry1] user_parameters=[]
[entry1_part] container=dataframe
[entry1_part] description=entry1 part
[entry1_part] direct_access=allow
[entry1_part] user_parameters=[{'default': '1', 'allowed': ['1', '2'], 'type': u'str', 'name': u'part', 'description': u'part of filename'}]
[use_example1] container=dataframe
[use_example1] description=example1 source plugin
[use_example1] direct_access=forbid
[use_example1] user_parameters=[]
Describe
Given the name of a catalog entry, this subcommand lists the details of the respective
catalog entry.
>>> intake describe --help
usage: intake describe [-h] URI NAME
positional arguments:
URI Catalog URI
NAME Catalog name
optional arguments:
-h, --help show this help message and exit
>>> intake describe intake/catalog/tests/catalog1.yml entry1
[entry1] container=dataframe
[entry1] description=entry1 full
[entry1] direct_access=forbid
[entry1] user_parameters=[]
Discover
Given the name of a catalog entry, this subcommand returns a key-value description of the
data source. The exact details are subject to change.
>>> intake discover --help
usage: intake discover [-h] URI NAME
positional arguments:
URI Catalog URI
NAME Catalog name
optional arguments:
-h, --help show this help message and exit
>>> intake discover intake/catalog/tests/catalog1.yml entry1
{'npartitions': 2, 'dtype': dtype([('name', 'O'), ('score', '<f8'), ('rank', '<i8')]), 'shape': (None,), 'datashape':None, 'metadata': {'foo': 'bar', 'bar': [1, 2, 3]}}
Exists
Given the name of a catalog entry, this subcommand returns whether or not the respective
catalog entry is valid.
>>> intake exists --help
usage: intake exists [-h] URI NAME
positional arguments:
URI Catalog URI
NAME Catalog name
optional arguments:
-h, --help show this help message and exit
>>> intake exists intake/catalog/tests/catalog1.yml entry1
True
>>> intake exists intake/catalog/tests/catalog1.yml entry2
False
Get
Given the name of a catalog entry, this subcommand outputs the entire data source to
standard output.
>>> intake get --help
usage: intake get [-h] URI NAME
positional arguments:
URI Catalog URI
NAME Catalog name
optional arguments:
-h, --help show this help message and exit
>>> intake get intake/catalog/tests/catalog1.yml entry1
name score rank
0 Alice1 100.5 1
1 Bob1 50.3 2
2 Charlie1 25.0 3
3 Eve1 25.0 3
4 Alice2 100.5 1
5 Bob2 50.3 2
6 Charlie2 25.0 3
7 Eve2 25.0 3
Config and Cache
CLI functions starting with intake cache and intake config are available to provide
information about the system: the locations and value of configuration parameters, and the
state of cached files.
Persisting Data
(this is an experimental new feature, expect enhancements and changes)
Introduction
As defined in the glossary, to Persist is to convert data into the storage format most
appropriate for the container type, and save a copy of this for rapid lookup in the
future. This is of great potential benefit where the creation or transfer of the original
data source takes some time.
This is not to be confused with the file Cache.
Usage
Any Data Source has a method .persist(). The only option that you will need to pick is a
TTL, the number of seconds that the persisted version lasts before expiry (leave as None
for no expiry). This creates a local copy in the persist directory, which may be in
"~/.intake/persist, but can be configured.
Each container type (dataframe, array, ...) will have its own implementation of
persistence, and a particular file storage format associated. The call to .persist() may
take arguments to tune how the local files are created, and in some cases may require
additional optional packages to be installed.
Example:
cat = intake.open_catalog('mycat.yaml') # load a remote cat
source = cat.csvsource() # source pointing to remote data
source.persist()
source = cat.csvsource() # future use now gives local intake_parquet.ParquetSource
To control whether a catalog will automatically give you the persisted version of a source
in this way using the argument persist_mode, e.g., to ignore locally persisted versions,
you could have done:
cat = intake.open_catalog('mycat.yaml', persist_mode='never')
or
source = cat.csvsource(persist_mode='never')
Note that if you give a TTL (in seconds), then the original source will be accessed and a
new persisted version written transparently when the old persisted version has expired.
Note that after persisting, the original source will have source.has_been_persisted ==
True and the persisted source (i.e., the one loaded from local files) will have
source.is_persisted == True.
Export
A similar concept to Persist, Export allows you to make a copy of some data source, in the
format appropriate for its container, and place this data-set in whichever location suits
you, including remote locations. This functionality (source.export()) does not touch the
persist store; instead, it returns a YAML text representation of the output, so that you
can put it into a catalog of your own. It would be this catalog that you share with other
people.
Note that "exported" data-sources like this do contain the information of the original
source they were made from in their metadata, so you can recreate the original source, if
you want to, and read from there.
Persisting to Remote
If you are typically running your code inside of ephemoral containers, then persisting
data-sets may be something that you want to do (because the original source is slow, or
parsing is CPU/memory intensive), but the local storage is not useful. In some cases you
may have access to some shared network storage mounted on the instance, but in other cases
you will want to persist to a remote store.
The config value 'persist_path', which can also be set by the environment variable
INTAKE_PERSIST_PATH can be a remote location such as s3://mybucket/intake-persist. You
will need to install the appropriate package to talk to the external storage (e.g., s3fs,
gcsfs, pyarrow), but otherwise everything should work as before, and you can access the
persisted data from any container.
The Persist Store
You can interact directly with the class implementing persistence:
from intake.container.persist import store
This singleton instance, which acts like a catalog, allows you to query the contents of
the instance store and to add and remove entries. It also allows you to find the original
source for any given persisted source, and refresh the persisted version on demand.
For details on the methods of the persist store, see the API documentation:
intake.container.persist.PersistStore(). Sources in the store carry a lot of information
about the sources they were made from, so that they can be remade successfully. This all
appears in the source metadata. The sources use the "token" of the original data source
as their key in the store, a value which can be found by dask.base.tokenize(source) for
the original source, or can be taken from the metadata of a persisted source.
Note that all of the information about persisted sources is held in a single YAML file in
the persist directory (typically /persisted/cat.yaml within the config directory, but see
intake.config.conf['persist_path']). This file can be edited by hand if you wanted to, for
example, set some persisted source not to expire. This is only recommended for experts.
Future Enhancements
• CLI functionality to investigate and alter the state of the persist store.
• Time check-pointing of persisted data, such that you can not only get the "most recent"
but any version in the time-series.
• (eventually) pipeline functionality, whereby a persisted data source depends on another
persisted data source, and the whole train can be refreshed on a schedule or on demand.
Plotting
Intake provides a plotting API based on the hvPlot library, which closely mirrors the
pandas plotting API but generates interactive plots using HoloViews and Bokeh.
The hvPlot website provides comprehensive documentation on using the plotting API to
quickly visualize and explore small and large datasets. The main features offered by the
plotting API include:
• Support for tabular data stored in pandas and dask dataframes
• Support for gridded data stored in xarray backed nD-arrays
• Support for plotting large datasets with datashader
Using Intake alongside hvPlot allows declaratively persisting plot declarations and
default options in the regular catalog.yaml files.
Setup
For detailed installation instructions see the getting started section in the hvPlot
documentation. To start with install hvplot using conda:
conda install -c conda-forge hvplot
or using pip:
pip install hvplot
Usage
The plotting API is designed to work well in and outside the Jupyter notebook, however
when using it in JupyterLab the PyViz lab extension must be installed first:
jupyter labextension install @pyviz/jupyterlab_pyviz
For detailed instructions on displaying plots in the notebook and from the Python command
prompt see the hvPlot user guide.
Python Command Prompt & Scripts
Assuming the US Crime dataset has been installed (in the intake-examples repo, or from
conda with conda install -c intake us_crime):
Once installed the plot API can be used, by using the .plot method on an intake
DataSource:
import intake
import hvplot as hp
crime = intake.cat.us_crime
columns = ['Burglary rate', 'Larceny-theft rate', 'Robbery rate', 'Violent Crime rate']
violin = crime.plot.violin(y=columns, group_label='Type of crime',
value_label='Rate per 100k', invert=True)
hp.show(violin)
[image]
Notebook
Inside the notebook plots will display themselves, however the notebook extension must be
loaded first. The extension may be loaded by importing hvplot.intake module or explicitly
loading the holoviews extension, or by calling intake.output_notebook():
# To load the extension run this import
import hvplot.intake
# Or load the holoviews extension directly
import holoviews as hv
hv.extension('bokeh')
# convenience function
import intake
intake.output_notebook()
crime = intake.cat.us_crime
columns = ['Violent Crime rate', 'Robbery rate', 'Burglary rate']
crime.plot(x='Year', y=columns, value_label='Rate (per 100k people)')
Predefined Plots
Some catalogs will define plots appropriate to a specific data source. These will be
specified such that the user gets the right view with the right columns and labels,
without having to investigate the data in detail -- this is ideal for quick-look plotting
when browsing sources.
import intake
intake.us_crime.plots
Returns ['example']. This works whether accessing the entry object or the source instance.
To visualise
intake.us_crime.plot.example()
Persisting metadata
Intake allows catalog yaml files to declare metadata fields for each data source which are
made available alongside the actual dataset. The plotting API reserves certain fields to
define default plot options, to label and annotate the data fields in a dataset and to
declare pre-defined plots.
Declaring defaults
The first set of metadata used by the plotting API is the plot field in the metadata
section. Any options found in the metadata field will apply to all plots generated from
that data source, allowing the definition of plotting defaults. For example when plotting
a fairly large dataset such as the NYC Taxi data, it might be desirable to enable
datashader by default ensuring that any plot that supports it is datashaded. The syntax to
declare default plot options is as follows:
sources:
nyc_taxi:
description: NYC Taxi dataset
driver: parquet
args:
urlpath: 's3://datashader-data/nyc_taxi_wide.parq'
metadata:
plot:
datashade: true
Declaring data fields
The columns of a CSV or parquet file or the coordinates and data variables in a NetCDF
file often have shortened, or cryptic names with underscores. They also do not provide
additional information about the units of the data or the range of values, therefore the
catalog yaml specification also provides the ability to define additional information
about the fields in a dataset.
Valid attributes that may be defined for the data fields include:
• label: A readable label for the field which will be used to label axes and widgets
• unit: A unit associated with the values inside a data field
• range: A range associated with a field declaring limits which will override those
computed from the data
Just like the default plot options the fields may be declared under the metadata section
of a data source:
sources:
nyc_taxi:
description: NYC Taxi dataset
driver: parquet
args:
urlpath: 's3://datashader-data/nyc_taxi_wide.parq'
metadata:
fields:
dropoff_x:
label: Longitude
dropoff_y:
label: Latitude
total_fare:
label: Fare
unit: $
Declaring custom plots
As shown in the hvPlot user guide, the plotting API provides a variety of plot types,
which can be declared using the kind argument or via convenience methods on the plotting
API, e.g. cat.source.plot.scatter(). In addition to declaring default plot options and
field metadata data sources may also declare custom plot, which will be made available as
methods on the plotting API. In this way a catalogue may declare any number of custom
plots alongside a datasource.
To make this more concrete consider the following custom plot declaration on the plots
field in the metadata section:
sources:
nyc_taxi:
description: NYC Taxi dataset
driver: parquet
args:
urlpath: 's3://datashader-data/nyc_taxi_wide.parq'
metadata:
plots:
dropoff_scatter:
kind: scatter
x: dropoff_x
y: dropoff_y
datashade: True
width: 800
height: 600
This declarative specification creates a new custom plot called dropoff_scatter, which
will be available on the catalog under cat.nyc_taxi.plot.dropoff_scatter(). Calling this
method on the plot API will automatically generate a datashaded scatter plot of the
dropoff locations in the NYC taxi dataset.
Of course the three metadata fields may also be used together, declaring global defaults
under the plot field, annotations for the data fields under the fields key and custom
plots via the plots field.
Plugin Directory
This is a list of known projects which install driver plugins for Intake, and the named
drivers each contains in parentheses:
• builtin to Intake (catalog, csv, intake_remote, ndzarr, numpy, textfiles, yaml_file_cat,
yaml_files_cat, zarr_cat, json, jsonl)
• intake-astro Table and array loading of FITS astronomical data (fits_array, fits_table)
• intake-accumulo Apache Accumulo clustered data storage (accumulo)
• intake-avro: Apache Avro data serialization format (avro_table, avro_sequence)
• intake-bluesky: search and retrieve data in the bluesky data model
• intake-dcat Browse and load data from DCAT catalogs. (dcat)
• intake-dynamodb link to Amazon DynamoDB (dynamodb)
• intake-elasticsearch: Elasticsearch search and analytics engine (elasticsearch_seq,
elasticsearch_table)
• intake-esm: Plugin for building and loading intake catalogs for earth system data sets
holdings, such as CMIP (Coupled Model Intercomparison Project) and CESM Large Ensemble
datasets.
• intake-geopandas: load from ESRI Shape Files, GeoJSON, and geospatial databases with
geopandas (geojson, postgis, shapefile, spatialite) and regionmask for opening
shapefiles into regionmask.
• intake-google-analytics: run Google Analytics queries and load data as a DataFrame
(google_analytics_query)
• intake-hbase: Apache HBase database (hbase)
• intake-iris load netCDF and GRIB files with IRIS (grib, netcdf)
• intake-metabase: Generate catalogs and load tables as DataFrames from Metabase
(metabase_catalog, metabase_table)
• intake-mongo: MongoDB noSQL query (mongo)
• intake-nested-yaml-catalog: Plugin supporting a single YAML hierarchical catalog to
organize datasets and avoid a data swamp. (nested_yaml_cat)
• intake-netflow: Netflow packet format (netflow)
• intake-notebook: Experimental plugin to access parameterised notebooks through intake
and executed via papermill (ipynb)
• intake-odbc: ODBC database (odbc)
• intake-parquet: Apache Parquet file format (parquet)
• intake-pattern-catalog: Plugin for specifying a file-path pattern which can represent a
number of different entries (pattern_cat)
• intake-pcap: PCAP network packet format (pcap)
• intake-postgres: PostgreSQL database (postgres)
• intake-s3-manifests (s3_manifest)
• intake-salesforce: Generate catalogs and load tables as DataFrames from Salesforce
(salesforce_catalog, salesforce_table)
• intake-sklearn: Load scikit-learn models from Pickle files (sklearn)
• intake-solr: Apache Solr search platform (solr)
• intake-stac: Intake Driver for SpatioTemporal Asset Catalogs (STAC).
• intake-stripe: Generate catalogs and load tables as DataFrames from Stripe
(stripe_catalog, stripe_table)
• intake-spark: data processed by Apache Spark (spark_cat, spark_rdd, spark_dataframe)
• intake-sql: Generic SQL queries via SQLAlchemy (sql_cat, sql, sql_auto, sql_manual)
• intake-splunk: Splunk machine data query (splunk)
• intake-streamz: real-time event processing using Streamz (streamz)
• intake-thredds: Intake interface to THREDDS data catalogs (thredds_cat,
thredds_merged_source)
• intake-xarray: load netCDF, Zarr and other multi-dimensional data (xarray_image, netcdf,
grib, opendap, rasterio, remote-xarray, zarr)
The status of these projects is available at Status Dashboard.
Don't see your favorite format? See making-plugins for how to create new plugins.
Note that if you want your plugin listed here, open an issue in the Intake issue
repository and add an entry to the status dashboard repository. We also have a plugin
wishlist Github issue that shows the breadth of plugins we hope to see for Intake.
Server Protocol
This page gives deeper details on how the Intake server is implemented. For those simply
wishing to run and configure a server, see the tools section.
Communication between the intake client and server happens exclusively over HTTP, with all
parameters passed using msgpack UTF8 encoding. The server side is implemented by the
module intake.cli.server. Currently, only the following two routes are available:
• http://server:port/v1/info
• http://server:port/v1/source.
The server may be configured to use auth services, which, when passed the header of the
incoming call, can determine whether the given request is allowed. See auth-plugins.
GET /info
Retrieve information about the data-sets available on this server. The list of data-sets
may be paginated, in order to avoid excessively long transactions. Notice that the catalog
for which a listing is being requested can itself be a data-source (when source-id is
passed) - this is how nested sub-catalogs are handled on the server.
Parameters
• page_size, int or none (optional): to enable pagination, set this value. The number of
entries returned will be this value at most. If None, returns all entries. This is
passed as a query parameter.
• page_offset, int (optional): when paginating, start the list from this numerical offset.
The order of entries is guaranteed if the base catalog has not changed. This is passed
as a query parameter.
• source-id, uuid string (optional): when the catalog being accessed is not the route
catalog, but an open data-source on the server, this is its unique identifier. See POST
/source for how these IDs are generated. If the catalog being accessed is the root
Catalog, this parameter should be omitted. This is passed as an HTTP header.
Returns
• version, string: the server's Intake version
• sources, list of objects: the main payload, where each object contains a name, and the
result of calling .describe() on the corresponding data-source, i.e., the container
type, description, metadata.
• metadata, object: any metadata associated with the whole catalog
GET /source
Fetch information about a specific source. This is the random-access variant of the GET
/info route, by which a particular data-source can be accessed without paginating through
all of the sources.
Parameters
• name, string (required): the data source name being accessed, one of the members of the
catalog. This is passed as a query parameter.
• source-id, uuid string (optional): when the catalog being accessed is not the root
catalog, but an open data-source on the server, this is its unique identifier. See POST
/source for how these IDs are generated. If the catalog being accessed is the root
Catalog, this parameter should be omitted. This is passed as an HTTP header.
Returns
Same as one of the entries in sources for GET /info: the result of .describe() on the
given data-source in the server
POST /source, action="search"
Searching a Catalog returns search results in the form of a new Catalog. This "results"
Catalog is cached on the server the same as any other Catalog.
Parameters
• source-id, uuid string (optional): When the catalog being searched is not the root
catalog, but a subcatalog on the server, this is its unique identifier. If the catalog
being searched is the root Catalog, this parameter should be omitted. This is passed as
an HTTP header.
• query: tuple of (args, kwargs): These will be unpacked into Catalog.search on the server
to create the "results" Catalog. This is passed in the body of the message.
Returns
• source_id, uuid string: the identifier of the results Catalog in the server's source
cache
POST /source, action="open"
This is a more involved processing of a data-source, and, if successful, returns one of
two possible scenarios:
• direct-access, in which all the details required for reading the data directly from the
client are passed, and the client then creates a local copy of the data source and needs
no further involvement from the server in order to fetch the data
• remote-access, in which the client is unable or unwilling to create a local version of
the data-source, and instead created a remote data-source which will fetch the data for
each partition from the server.
The set of parameters supplied and the server/client policies will define which method of
access is employed. In the case of remote-access, the data source is instantiated on the
server, and .discover() run on it. The resulting information is passed back, and must be
enough to instantiate a subclass of intake.container.base.RemoteSource appropriate for the
container of the data-set in question (e.g., RemoteArray when container="ndarray"). In
this case, the response also includes a UUID string for the open instance on the server,
referencing the cache of open sources maintained by the server.
Note that "opening" a data entry which is itself is a catalog implies instantiating that
catalog object on the server and returning its UUID, such that a listing can be made using
GET/ info or GET /source.
Parameters
• name, string (required): the data source name being accessed, one of the members of the
catalog. This is passed in the body of the request.
• source-id, uuid string (optional): when the catalog being accessed is not the root
catalog, but an open data-source on the server, this is its unique identifier. If the
catalog being accessed is the root Catalog, this parameter should be omitted. This is
passed as an HTTP header.
• available_plugins, list of string (optional): the set of named data drivers supported by
the client. If the driver required by the data-source is not supported by the client,
then the source must be opened remote-access. This is passed in the body of the request.
• parameters, object (optional): user parameters to pass to the data-source when
instantiating. Whether or not direct-access is possible may, in principle, depend on
these parameters, but this is unlikely. Note that some parameter default value functions
are designed to be evaluated on the server, which may have access to, for example, some
credentials service (see paramdefs). This is passed in the body of the request.
Returns
If direct-access, the driver plugin name and set of arguments for instantiating the
data-soruce in the client.
If remote-access, the data-source container, schema and source-ID so that further reads
can be made from the server.
POST /source, action="read"
This route fetches data from the server once a data-source has been opened in
remote-access mode.
Parameters
• source-id, uuid string (required): the identifier of the data-source in the server's
source cache. This is returned when action="open". This is passed in the body of the
request.
• partition, int or tuple (optional, but necessary for some sources): section/chunk of the
data to fetch. In cases where the data-source is partitioned, the client will fetch the
data one partition at a time, so that it will appear partitioned in the same manner on
the client side for iteration of passing to Dask. Some data-sources do not support
partitioning, and then this parameter is not required/ignored. This is passed in the
body of the request.
• accepted_formats, accepted_compression, list of strings (required): to specify how
serialization of data happens. This is an expert feature, see docs in the module
intake.container.serializer. This is passed in the body of the request.
Dataset Transforms
aka. derived datasets.
WARNING:
experimental feature, the API may change. The data sources in intake.source.derived are
not yet declared as top-level named drivers in the package entrypoints.
Intake allows for the definition of data sources which take as their input another source
in the same directory, so that you have the opportunity to present processing to the user
of the catalog.
The "target" or a derived data source will normally be a string. In the simple case, it is
the name of a data source in the same catalog. However, we use the syntax "catalog:source"
to refer to sources in other catalogs, where the part before ":" will be passed to
intake.open_catalog(), together with any keyword arguments from cat_kwargs.
This can be done by defining classes which inherit from
intake.source.derived.DerivedSource, or using one of the pre-defined classes in the same
module, which usually need to be passed a reference to a function in a python module. We
will demonstrate both.
Example
Consider the following target dataset, which loads some simple facts about US states from
a CSV file. This example is taken from the Intake test suite.
We now show two ways to apply a super-simple transform to this data, which selects two of
the dataframe's columns.
Class Example
The first version uses an approach in which the transform is derived in a data source
class, and the parameters passed are specific to the transform type. Note that the driver
is referred to by it's fully-qualified name in the Intake package.
The source class for this is included in the Intake codebase, but the important part is:
class Columns(DataFrameTransform):
...
def pick_columns(self, df):
return df[self._params["columns"]]
We see that this specific class inherits from DataFrameTransform, with
transform=self.pick_columns. We know that the inputs and outputs are both dataframes. This
allows for some additional validation and an automated way to infer the output dataframe's
schema that reduces the number of line of code required.
The given method does exactly what you might imagine: it takes and input dataframe and
applies a column selection to it.
Running cat.derive_cols.read() will indeed, as expected, produce a version of the data
with only the selected columns included. It does this by defining the original dataset,
appying the selection, and then getting Dask to generate the output. For some datasets,
this can mean that the selection is pushed down to the reader, and the data for the
dropped columns is never loaded. The user may choose to do .to_dask() instead, and
manipulate the lazy dataframe directly, before loading.
Functional Example
This second version of the same output uses the more generic and flexible
intake.source.derived.DataFrameTransform.
derive_cols_func:
driver: intake.source.derived.DataFrameTransform
args:
targets:
- input_data
transform: "intake.source.tests.test_derived._pick_columns"
transform_kwargs:
columns: ["state", "slug"]
In this case, we pass a reference to a function defined in the Intake test suite.
Normally this would be declared in user modules, where perhaps those declarations and
catalog(s) are distributed together as a package.
def _pick_columns(df, columns):
return df[columns]
This is, of course, very similar to the method shown in the previous section, and again
applies the selection in the given named argument to the input. Note that Intake does not
support including actual code in your catalog, since we would not want to allow arbitrary
execution of code on catalog load, as opposed to execution.
Loading this data source proceeds exactly the same way as the class-based approach, above.
Both Dask and in-memory (Pandas, via .read()) methods work as expected. The declaration
in YAML, above, is slightly more verbose, but the amount of code is smaller. This
demonstrates a tradeoff between flexibility and concision. If there were validation code
to add for the arguments or input dataset, it would be less obvious where to put these
things.
Barebone Example
The previous two examples both did dateframe to dataframe transforms. However, totally
arbitrary computations are possible. Consider the following:
barebones:
driver: intake.source.derived.GenericTransform
args:
targets:
- input_data
transform: builtins.len
transform_kwargs: {}
This applies len to the input dataframe. cat.barebones.describe() gives the output
container type as "other", i.e., not specified. The result of read() on this gives the
single number 50, the number of rows in the input data. This class, and DerivedDataSource
and included with the intent as superclasses, and probably will not be used directly
often.
Execution engine
None of the above example specified explicitly where the compute implied by the
transformation will take place. However, most Intake drivers support in-memory containers
and Dask; remembering that the input dataset here is a dataframe. However, the behaviour
is defined in the driver class itself - so it would be fine to write a driver in which we
make different assumptions. Let's suppose, for instance, that the original source is to be
loaded from spark (see the intake-spark package), the driver could explicitly call
.to_spark on the original source, and be assured that it has a Spark object to work with.
It should, of course, explain in its documentation what assumptions are being made and
that, presumably, the user is expected to also call .to_spark if they wished to directly
manipulate the spark object.
API
───────────────────────────────────────────────────────────────────────────────────
intake.source.derived.DerivedSource(*args, Base source deriving from
...) another source in the same
catalog
───────────────────────────────────────────────────────────────────────────────────
intake.source.derived.GenericTransform(...)
───────────────────────────────────────────────────────────────────────────────────
intake.source.derived.DataFrameTransform(...) Transform where the input and
output are both Dask-compatible
dataframes
───────────────────────────────────────────────────────────────────────────────────
intake.source.derived.Columns(*args, Simple dataframe transform to
**kwargs) pick columns
┌──────────────────────────────────────────────┬──────────────────────────────────┐
│ │ │
--
REFERENCE
API
Auto-generated reference
End User
These are reference class and function definitions likely to be useful to everyone.
┌─────────────────────────────────────────────────┬──────────────────────────────────┐
│intake.open_catalog([uri]) │ Create a Catalog object │
├─────────────────────────────────────────────────┼──────────────────────────────────┤
│intake.registry │ │
├─────────────────────────────────────────────────┼──────────────────────────────────┤
│intake.register_driver(name, │ Add a driver to intake.registry. │
│driver[, overwrite]) │ │
├─────────────────────────────────────────────────┼──────────────────────────────────┤
│intake.unregister_driver(name) │ Ensure that a given name in the │
│ │ registry is cleared. │
├─────────────────────────────────────────────────┼──────────────────────────────────┤
│intake.upload(data, path, │ Given a concrete data object, │
│**kwargs) │ store it at given location │
│ │ return Source │
├─────────────────────────────────────────────────┼──────────────────────────────────┤
│intake.source.csv.CSVSource(*args, │ Read CSV files into dataframes │
│**kwargs) │ │
├─────────────────────────────────────────────────┼──────────────────────────────────┤
│intake.source.textfiles.TextFilesSource(...) │ Read textfiles as sequence of │
│ │ lines │
├─────────────────────────────────────────────────┼──────────────────────────────────┤
│intake.source.jsonfiles.JSONFileSource(...) │ Read JSON files as a single │
│ │ dictionary or list │
├─────────────────────────────────────────────────┼──────────────────────────────────┤
│intake.source.jsonfiles.JSONLinesFileSource(...) │ Read a JSONL (‐ │
│ │ https://jsonlines.org/) file and │
│ │ return a list of objects, each │
│ │ being valid json object (e.g. │
├─────────────────────────────────────────────────┼──────────────────────────────────┤
│intake.source.npy.NPySource(*args, **kwargs) │ Read numpy binary files into an │
│ │ array │
├─────────────────────────────────────────────────┼──────────────────────────────────┤
│intake.source.zarr.ZarrArraySource(*args, ...) │ Read Zarr format files into an │
│ │ array │
└─────────────────────────────────────────────────┴──────────────────────────────────┘
│intake.catalog.local.YAMLFileCatalog(*args, ...) │ Catalog as described by a single │
│ │ YAML file │
├─────────────────────────────────────────────────┼──────────────────────────────────┤
│intake.catalog.local.YAMLFilesCatalog(*args, │ Catalog as described by a │
│...) │ multiple YAML files │
├─────────────────────────────────────────────────┼──────────────────────────────────┤
│intake.catalog.zarr.ZarrGroupCatalog(*args, ...) │ A catalog of the members of a │
│ │ Zarr group. │
└─────────────────────────────────────────────────┴──────────────────────────────────┘
intake.open_catalog(uri=None, **kwargs)
Create a Catalog object
Can load YAML catalog files, connect to an intake server, or create any arbitrary
Catalog subclass instance. In the general case, the user should supply driver= with
a value from the plugins registry which has a container type of catalog. File
locations can generally be remote, if specifying a URL protocol.
The default behaviour if not specifying the driver is as follows:
• if uri is a a single string ending in "yml" or "yaml", open it as a catalog file
• if uri is a list of strings, a string containing a glob character ("*") or a
string not ending in "y(a)ml", open as a set of catalog files. In the latter
case, assume it is a directory.
• if uri beings with protocol "intake:", connect to a remote Intake server
• if uri is None or missing, create a base Catalog object without entries.
Parameters
uri: str or pathlib.Path
Designator for the location of the catalog.
kwargs:
passed to subclass instance, see documentation of the individual
catalog classes. For example, yaml_files_cat (when specifying
multiple uris or a glob string) takes the additional parameter
flatten=True|False, specifying whether all data sources are merged in
a single namespace, or each file becomes a sub-catalog.
SEE ALSO:
intake.open_yaml_files_cat, intake.open_yaml_file_cat
intake.open_intake_remote
intake.registry
Mapping from plugin names to the DataSource classes that implement them. These are
the names that should appear in the driver: key of each source definition in a
catalog. See plugin-directory for more details.
intake.open_
Set of functions, one for each plugin, for direct opening of a data source. The
names are derived from the names of the plugins in the registry at import time.
intake.upload(data, path, **kwargs)
Given a concrete data object, store it at given location return Source
Use this function to publicly share data which you have created in your python
session. Intake will try each of the container types, to see if one of them can
handle the input data, and write the data to the path given, in the format most
appropriate for the data type, e.g., parquet for pandas or dask data-frames.
With the DataSource instance you get back, you can add this to a catalog, or just
get the YAML representation for editing (.yaml()) and sharing.
Parameters
data instance The object to upload and store. In many cases, the dask or
in-memory variant are handled equivalently.
path str Location of the output files; can be, for instance, a network
drive for sharing over a VPC, or a bucket on a cloud storage service
kwargs passed to the writer for fine control.UNINDENT
Returns
DataSource instance
Source classes
class intake.source.csv.CSVSource(*args, **kwargs)
Read CSV files into dataframes
Prototype of sources reading dataframe data
__init__(urlpath, csv_kwargs=None, metadata=None, storage_options=None,
path_as_pattern=True)
Parameters
urlpath
str or iterable, location of data May be a local path, or
remote path if including a protocol specifier such as 's3://'.
May include glob wildcards or format pattern strings. Some
examples:
• {{ CATALOG_DIR }}data/precipitation.csv
• s3://data/*.csv
• s3://data/precipitation_{state}_{zip}.csv
• s3://data/{year}/{month}/{day}/precipitation.csv
• {{ CATALOG_DIR }}data/precipitation_{date:%Y-%m-%d}.csv
csv_kwargs
dict Any further arguments to pass to Dask's read_csv (such as
block size) or to the CSV parser in pandas (such as which
columns to use, encoding, data-types)
storage_options
dict Any parameters that need to be passed to the remote data
backend, such as credentials.
path_as_pattern
bool or str, optional Whether to treat the path as a pattern
(ie. data_{field}.csv) and create new columns in the output
corresponding to pattern fields. If str, is treated as pattern
to match on. Default is True.
discover()
Open resource and populate the source attributes.
export(path, **kwargs)
Save this data for sharing with other people
Creates a copy of the data in a format appropriate for its container, in the
location specified (which can be remote, e.g., s3).
Returns the resultant source object, so that you can, for instance, add it
to a catalog (catalog.add(source)) or get its YAML representation (.yaml()).
persist(ttl=None, **kwargs)
Save data from this source to local persistent storage
Parameters
ttl: numeric, optional
Time to live in seconds. If provided, the original source will
be accessed and a new persisted version written transparently
when more than ttl seconds have passed since the old persisted
version was written.
kargs: passed to the _persist method on the base container.
read() Load entire dataset into a container and return it
read_partition(i)
Return a part of the data corresponding to i-th partition.
By default, assumes i should be an integer between zero and npartitions;
override for more complex indexing schemes.
to_dask()
Return a dask container for this data source
class intake.source.zarr.ZarrArraySource(*args, **kwargs)
Read Zarr format files into an array
Zarr is an numerical array storage format which works particularly well with remote
and parallel access. For specifics of the format, see
https://zarr.readthedocs.io/en/stable/
__init__(urlpath, storage_options=None, component=None, metadata=None, **kwargs)
The parameters dtype and shape will be determined from the first file, if
not given.
Parameters
urlpath
str Location of data file(s), possibly including protocol
information
storage_options
dict Passed on to storage backend for remote files
component
str or None If None, assume the URL points to an array. If
given, assume the URL points to a group, and descend the group
to find the array at this location in the hierarchy.
kwargs passed on to dask.array.from_zarr.UNINDENT
discover()
Open resource and populate the source attributes.
export(path, **kwargs)
Save this data for sharing with other people
Creates a copy of the data in a format appropriate for its container,
in the location specified (which can be remote, e.g., s3).
Returns the resultant source object, so that you can, for instance,
add it to a catalog (catalog.add(source)) or get its YAML
representation (.yaml()).
persist(ttl=None, **kwargs)
Save data from this source to local persistent storage
Parameters
ttl: numeric, optional
Time to live in seconds. If provided, the original
source will be accessed and a new persisted version
written transparently when more than ttl seconds have
passed since the old persisted version was written.
kargs: passed to the _persist method on the base container.
read() Load entire dataset into a container and return it
read_partition(i)
Return a part of the data corresponding to i-th partition.
By default, assumes i should be an integer between zero and
npartitions; override for more complex indexing schemes.
to_dask()
Return a dask container for this data source
class intake.source.textfiles.TextFilesSource(*args, **kwargs)
Read textfiles as sequence of lines
Prototype of sources reading sequential data.
Takes a set of files, and returns an iterator over the text in each of them. The
files can be local or remote. Extra parameters for encoding, etc., go into
storage_options.
__init__(urlpath, text_mode=True, text_encoding='utf8', compression=None,
decoder=None, read=True, metadata=None, storage_options=None)
Parameters
urlpath
str or list(str) Target files. Can be a glob-path (with "*")
and include protocol specified (e.g., "s3://"). Can also be a
list of absolute paths.
text_mode
bool Whether to open the file in text mode, recoding binary
characters on the fly
text_encoding
str If text_mode is True, apply this encoding. UTF* is by far
the most common
compression
str or None If given, decompress the file with the given codec
on load. Can be something like "gzip", "bz2", or to try to
guess from the filename, 'infer'
decoder
function, str or None Use this to decode the contents of
files. If None, you will get a list of lines of text/bytes. If
a function, it must operate on an open file-like object or a
bytes/str instance, and return a list
read bool If decoder is not None, this flag controls whether
bytes/str get passed to the function indicated (True) or the
open file-like object (False)
storage_options: dict
Options to pass to the file reader backend, including
text-specific encoding arguments, and parameters specific to
the remote file-system driver, if using.
discover()
Open resource and populate the source attributes.
export(path, **kwargs)
Save this data for sharing with other people
Creates a copy of the data in a format appropriate for its container, in the
location specified (which can be remote, e.g., s3).
Returns the resultant source object, so that you can, for instance, add it
to a catalog (catalog.add(source)) or get its YAML representation (.yaml()).
persist(ttl=None, **kwargs)
Save data from this source to local persistent storage
Parameters
ttl: numeric, optional
Time to live in seconds. If provided, the original source will
be accessed and a new persisted version written transparently
when more than ttl seconds have passed since the old persisted
version was written.
kargs: passed to the _persist method on the base container.
read() Load entire dataset into a container and return it
read_partition(i)
Return a part of the data corresponding to i-th partition.
By default, assumes i should be an integer between zero and npartitions;
override for more complex indexing schemes.
to_dask()
Return a dask container for this data source
class intake.source.jsonfiles.JSONFileSource(*args, **kwargs)
Read JSON files as a single dictionary or list
The files can be local or remote. Extra parameters for encoding, etc., go into
storage_options.
__init__(urlpath: str, text_mode: bool = True, text_encoding: str = 'utf8',
compression: Optional[str] = None, read: bool = True, metadata: Optional[dict] =
None, storage_options: Optional[dict] = None)
Parameters
urlpath
str Target file. Can include protocol specified (e.g.,
"s3://").
text_mode
bool Whether to open the file in text mode, recoding binary
characters on the fly
text_encoding
str If text_mode is True, apply this encoding. UTF* is by far
the most common
compression
str or None If given, decompress the file with the given codec
on load. Can be something like "zip", "gzip", "bz2", or to try
to guess from the filename, 'infer'
storage_options: dict
Options to pass to the file reader backend, including
text-specific encoding arguments, and parameters specific to
the remote file-system driver, if using.
discover()
Open resource and populate the source attributes.
export(path, **kwargs)
Save this data for sharing with other people
Creates a copy of the data in a format appropriate for its container, in the
location specified (which can be remote, e.g., s3).
Returns the resultant source object, so that you can, for instance, add it
to a catalog (catalog.add(source)) or get its YAML representation (.yaml()).
persist(ttl=None, **kwargs)
Save data from this source to local persistent storage
Parameters
ttl: numeric, optional
Time to live in seconds. If provided, the original source will
be accessed and a new persisted version written transparently
when more than ttl seconds have passed since the old persisted
version was written.
kargs: passed to the _persist method on the base container.
read() Load entire dataset into a container and return it
class intake.source.jsonfiles.JSONLinesFileSource(*args, **kwargs)
Read a JSONL (https://jsonlines.org/) file and return a list of objects, each being
valid json object (e.g. a dictionary or list)
__init__(urlpath: str, text_mode: bool = True, text_encoding: str = 'utf8',
compression: Optional[str] = None, read: bool = True, metadata: Optional[dict] =
None, storage_options: Optional[dict] = None)
Parameters
urlpath
str Target file. Can include protocol specified (e.g.,
"s3://").
text_mode
bool Whether to open the file in text mode, recoding binary
characters on the fly
text_encoding
str If text_mode is True, apply this encoding. UTF* is by far
the most common
compression
str or None If given, decompress the file with the given codec
on load. Can be something like "zip", "gzip", "bz2", or to try
to guess from the filename, 'infer'.
storage_options: dict
Options to pass to the file reader backend, including
text-specific encoding arguments, and parameters specific to
the remote file-system driver, if using.
discover()
Open resource and populate the source attributes.
export(path, **kwargs)
Save this data for sharing with other people
Creates a copy of the data in a format appropriate for its container, in the
location specified (which can be remote, e.g., s3).
Returns the resultant source object, so that you can, for instance, add it
to a catalog (catalog.add(source)) or get its YAML representation (.yaml()).
head(nrows: int = 100)
return the first nrows lines from the file
persist(ttl=None, **kwargs)
Save data from this source to local persistent storage
Parameters
ttl: numeric, optional
Time to live in seconds. If provided, the original source will
be accessed and a new persisted version written transparently
when more than ttl seconds have passed since the old persisted
version was written.
kargs: passed to the _persist method on the base container.
read() Load entire dataset into a container and return it
class intake.source.npy.NPySource(*args, **kwargs)
Read numpy binary files into an array
Prototype source showing example of working with arrays
Each file becomes one or more partitions, but partitioning within a file is only
along the largest dimension, to ensure contiguous data.
__init__(path, dtype=None, shape=None, chunks=None, storage_options=None,
metadata=None)
The parameters dtype and shape will be determined from the first file, if
not given.
Parameters
path: str of list of str
Location of data file(s), possibly including glob and protocol
information
dtype: str dtype spec
In known, the dtype (e.g., "int64" or "f4").
shape: tuple of int
If known, the length of each axis
chunks: int
Size of chunks within a file along biggest dimension - need
not be an exact factor of the length of that dimension
storage_options: dict
Passed to file-system backend.
discover()
Open resource and populate the source attributes.
export(path, **kwargs)
Save this data for sharing with other people
Creates a copy of the data in a format appropriate for its container, in the
location specified (which can be remote, e.g., s3).
Returns the resultant source object, so that you can, for instance, add it
to a catalog (catalog.add(source)) or get its YAML representation (.yaml()).
persist(ttl=None, **kwargs)
Save data from this source to local persistent storage
Parameters
ttl: numeric, optional
Time to live in seconds. If provided, the original source will
be accessed and a new persisted version written transparently
when more than ttl seconds have passed since the old persisted
version was written.
kargs: passed to the _persist method on the base container.
read() Load entire dataset into a container and return it
read_partition(i)
Return a part of the data corresponding to i-th partition.
By default, assumes i should be an integer between zero and npartitions;
override for more complex indexing schemes.
to_dask()
Return a dask container for this data source
class intake.catalog.local.YAMLFileCatalog(*args, **kwargs)
Catalog as described by a single YAML file
__init__(path, autoreload=True, **kwargs)
Parameters
path: str
Location of the file to parse (can be remote)
reload bool Whether to watch the source file for changes; make False
if you want an editable Catalog
export(path, **kwargs)
Save this data for sharing with other people
Creates a copy of the data in a format appropriate for its container, in the
location specified (which can be remote, e.g., s3).
Returns the resultant source object, so that you can, for instance, add it
to a catalog (catalog.add(source)) or get its YAML representation (.yaml()).
persist(ttl=None, **kwargs)
Save data from this source to local persistent storage
Parameters
ttl: numeric, optional
Time to live in seconds. If provided, the original source will
be accessed and a new persisted version written transparently
when more than ttl seconds have passed since the old persisted
version was written.
kargs: passed to the _persist method on the base container.
reload()
Reload catalog if sufficient time has passed
walk(sofar=None, prefix=None, depth=2)
Get all entries in this catalog and sub-catalogs
Parameters
sofar: dict or None
Within recursion, use this dict for output
prefix: list of str or None
Names of levels already visited
depth: int
Number of levels to descend; needed to truncate circular
references and for cleaner output
Returns
Dict where the keys are the entry names in dotted syntax, and the
values are entry instances.
class intake.catalog.local.YAMLFilesCatalog(*args, **kwargs)
Catalog as described by a multiple YAML files
__init__(path, flatten=True, **kwargs)
Parameters
path: str
Location of the files to parse (can be remote), including
possible glob (*) character(s). Can also be list of paths,
without glob characters.
flatten: bool (True)
Whether to list all entries in the cats at the top level
(True) or create sub-cats from each file (False).
export(path, **kwargs)
Save this data for sharing with other people
Creates a copy of the data in a format appropriate for its container, in the
location specified (which can be remote, e.g., s3).
Returns the resultant source object, so that you can, for instance, add it
to a catalog (catalog.add(source)) or get its YAML representation (.yaml()).
persist(ttl=None, **kwargs)
Save data from this source to local persistent storage
Parameters
ttl: numeric, optional
Time to live in seconds. If provided, the original source will
be accessed and a new persisted version written transparently
when more than ttl seconds have passed since the old persisted
version was written.
kargs: passed to the _persist method on the base container.
reload()
Reload catalog if sufficient time has passed
walk(sofar=None, prefix=None, depth=2)
Get all entries in this catalog and sub-catalogs
Parameters
sofar: dict or None
Within recursion, use this dict for output
prefix: list of str or None
Names of levels already visited
depth: int
Number of levels to descend; needed to truncate circular
references and for cleaner output
Returns
Dict where the keys are the entry names in dotted syntax, and the
values are entry instances.
class intake.catalog.zarr.ZarrGroupCatalog(*args, **kwargs)
A catalog of the members of a Zarr group.
__init__(urlpath, storage_options=None, component=None, metadata=None,
consolidated=False, name=None)
Parameters
urlpath
str Location of data file(s), possibly including protocol
information
storage_options
dict, optional Passed on to storage backend for remote files
component
str, optional If None, build a catalog from the root group. If
given, build the catalog from the group at this location in
the hierarchy.
metadata
dict, optional Catalog metadata. If not provided, will be
populated from Zarr group attributes.
consolidated
bool, optional If True, assume Zarr metadata has been
consolidated.
export(path, **kwargs)
Save this data for sharing with other people
Creates a copy of the data in a format appropriate for its container, in the
location specified (which can be remote, e.g., s3).
Returns the resultant source object, so that you can, for instance, add it
to a catalog (catalog.add(source)) or get its YAML representation (.yaml()).
persist(ttl=None, **kwargs)
Save data from this source to local persistent storage
Parameters
ttl: numeric, optional
Time to live in seconds. If provided, the original source will
be accessed and a new persisted version written transparently
when more than ttl seconds have passed since the old persisted
version was written.
kargs: passed to the _persist method on the base container.
reload()
Reload catalog if sufficient time has passed
walk(sofar=None, prefix=None, depth=2)
Get all entries in this catalog and sub-catalogs
Parameters
sofar: dict or None
Within recursion, use this dict for output
prefix: list of str or None
Names of levels already visited
depth: int
Number of levels to descend; needed to truncate circular
references and for cleaner output
Returns
Dict where the keys are the entry names in dotted syntax, and the
values are entry instances.
Base Classes
This is a reference API class listing, useful mainly for developers.
┌─────────────────────────────────────────────┬──────────────────────────────────┐
│intake.source.base.DataSourceBase(*args, │ An object which can produce data │
│...) │ │
├─────────────────────────────────────────────┼──────────────────────────────────┤
│intake.source.base.DataSource(*args, │ A Data Source will all optional │
│**kwargs) │ functionality │
├─────────────────────────────────────────────┼──────────────────────────────────┤
│intake.source.base.PatternMixin() │ Helper class to provide │
│ │ file-name parsing abilities to a │
│ │ driver class │
├─────────────────────────────────────────────┼──────────────────────────────────┤
│intake.container.base.RemoteSource(*args, │ Base class for all DataSources │
│...) │ living on an Intake server │
├─────────────────────────────────────────────┼──────────────────────────────────┤
│intake.catalog.Catalog(*args, **kwargs) │ Manages a hierarchy of data │
│ │ sources as a collective unit. │
├─────────────────────────────────────────────┼──────────────────────────────────┤
│intake.catalog.entry.CatalogEntry(*args, │ A single item appearing in a │
│...) │ catalog │
├─────────────────────────────────────────────┼──────────────────────────────────┤
│intake.catalog.local.UserParameter(*args, │ A user-settable item that is │
│...) │ passed to a DataSource upon │
│ │ instantiation. │
├─────────────────────────────────────────────┼──────────────────────────────────┤
│intake.auth.base.BaseAuth(*args, │ Base class for authorization │
│**kwargs) │ │
├─────────────────────────────────────────────┼──────────────────────────────────┤
│intake.source.cache.BaseCache(driver, │ Provides utilities for managing │
│spec) │ cached data files. │
├─────────────────────────────────────────────┼──────────────────────────────────┤
│intake.source.base.Schema(**kwargs) │ Holds details of data │
│ │ description for any type of │
│ │ data-source │
├─────────────────────────────────────────────┼──────────────────────────────────┤
│intake.container.persist.PersistStore(*args, │ Specialised catalog for │
│...) │ persisted data-sources │
└─────────────────────────────────────────────┴──────────────────────────────────┘
class intake.source.base.DataSource(*args, **kwargs)
A Data Source will all optional functionality
When subclassed, child classes will have the base data source functionality, plus
caching, plotting and persistence abilities.
plot Accessor for HVPlot methods. See plotting for more details.
class intake.catalog.Catalog(*args, **kwargs)
Manages a hierarchy of data sources as a collective unit.
A catalog is a set of available data sources for an individual entity (remote
server, local file, or a local directory of files). This can be expanded to
include a collection of subcatalogs, which are then managed as a single unit.
A catalog is created with a single URI or a collection of URIs. A URI can either be
a URL or a file path.
Each catalog in the hierarchy is responsible for caching the most recent refresh
time to prevent overeager queries.
Attributes
metadata
dict Arbitrary information to carry along with the data source specs.
configure_new(**kwargs)
Create a new instance of this source with altered arguments
Enables the picking of options and re-evaluating templates from any
user-parameters associated with this source, or overriding any of the init
arguments.
Returns a new data source instance. The instance will be recreated from the
original entry definition in a catalog if this source was originally created
from a catalog.
discover()
Open resource and populate the source attributes.
filter(func)
Create a Catalog of a subset of entries based on a condition
WARNING:
This function operates on CatalogEntry objects not DataSource objects.
NOTE:
Note that, whatever specific class this is performed on, the return
instance is a Catalog. The entries are passed unmodified, so they will
still reference the original catalog instance and include its details
such as directory,.
Parameters
func function This should take a CatalogEntry and return True or
False. Those items returning True will be included in the new
Catalog, with the same entry names
Returns
Catalog
New catalog with Entries that still refer to their parents
force_reload()
Imperative reload data now
classmethod from_dict(entries, **kwargs)
Create Catalog from the given set of entries
Parameters
entries
dict-like A mapping of name:entry which supports dict-like
functionality, e.g., is derived from collections.abc.Mapping.
kwargs passed on the constructor Things like metadata, name; see
__init__.
Returns
Catalog instance
get(**kwargs)
Create a new instance of this source with altered arguments
Enables the picking of options and re-evaluating templates from any
user-parameters associated with this source, or overriding any of the init
arguments.
Returns a new data source instance. The instance will be recreated from the
original entry definition in a catalog if this source was originally created
from a catalog.
property gui
Source GUI, with parameter selection and plotting
items()
Get an iterator over (key, source) tuples for the catalog entries.
keys() Entry names in this catalog as an iterator (alias for __iter__)
pop(key)
Remove entry from catalog and return it
This relies on the _entries attribute being mutable, which it normally is.
Note that if a catalog automatically reloads, any entry removed here may
soon reappear
Parameters
key str Key to give the entry in the cat
reload()
Reload catalog if sufficient time has passed
save(url, storage_options=None)
Output this catalog to a file as YAML
Parameters
url str Location to save to, perhaps remote
storage_options
dict Extra arguments for the file-system
serialize()
Produce YAML version of this catalog.
Note that this is not the same as .yaml(), which produces a YAML block
referring to this catalog.
values()
Get an iterator over the sources for catalog entries.
walk(sofar=None, prefix=None, depth=2)
Get all entries in this catalog and sub-catalogs
Parameters
sofar: dict or None
Within recursion, use this dict for output
prefix: list of str or None
Names of levels already visited
depth: int
Number of levels to descend; needed to truncate circular
references and for cleaner output
Returns
Dict where the keys are the entry names in dotted syntax, and the
values are entry instances.
class intake.catalog.entry.CatalogEntry(*args, **kwargs)
A single item appearing in a catalog
This is the base class, used by local entries (i.e., read from a YAML file) and by
remote entries (read from a server).
describe()
Get a dictionary of attributes of this entry.
Returns: dict with keys
name: str
The name of the catalog entry.
container
str kind of container used by this data source
description
str Markdown-friendly description of data source
direct_access
str Mode of remote access: forbid, allow, force
user_parameters
list[dict] List of user parameters defined by this entry
get(**user_parameters)
Open the data source.
Equivalent to calling the catalog entry like a function.
Note: entry(), entry.attr, entry[item] check for persisted sources, but
directly calling .get() will always ignore the persisted store (equivalent
to self._pmode=='never').
Parameters
user_parameters
dict Values for user-configurable parameters for this data
source
Returns
DataSource
property has_been_persisted
For the source created with the given args, has it been persisted?
property plots
List custom associated quick-plots
class intake.container.base.RemoteSource(*args, **kwargs)
Base class for all DataSources living on an Intake server
to_dask()
Return a dask container for this data source
class intake.catalog.local.UserParameter(*args, **kwargs)
A user-settable item that is passed to a DataSource upon instantiation.
For string parameters, default may include special functions func(args), which may
be expanded from environment variables or by executing a shell command.
Parameters
name: str
the key that appears in the DataSource argument strings
description: str
narrative text
type: str
one of list (COERSION_RULES)
default: type value
same type as type. It a str, may include special functions env,
shell, client_env, client_shell.
min, max: type value
for validation of user input
allowed: list of type
for validation of user input
describe()
Information about this parameter
expand_defaults(client=False, getenv=True, getshell=True)
Compile env, client_env, shell and client_shell commands
validate(value)
Does value meet parameter requirements?
class intake.auth.base.BaseAuth(*args, **kwargs)
Base class for authorization
Subclass this and override the methods to implement a new type of auth.
This basic class allows all access.
allow_access(header, source, catalog)
Is the given HTTP header allowed to access given data source
Parameters
header: dict
The HTTP header from the incoming request
source: CatalogEntry
The data source the user wants to access.
catalog: Catalog
The catalog object containing this data source.
allow_connect(header)
Is the requests header given allowed to talk to the server
Parameters
header: dict
The HTTP header from the incoming request
get_case_insensitive(dictionary, key, default=None)
Case-insensitive search of a dictionary for key.
Returns the value if key match is found, otherwise default.
class intake.source.cache.BaseCache(driver, spec, catdir=None, cache_dir=None,
storage_options={})
Provides utilities for managing cached data files.
Providers of caching functionality should derive from this, and appear as entries
in registry. The principle methods to override are _make_files() and _load() and
_from_metadata().
clear_all()
Clears all cache and metadata.
clear_cache(urlpath)
Clears cache and metadata for a given urlpath.
Parameters
urlpath: str, location of data
May be a local path, or remote path if including a protocol
specifier such as 's3://'. May include glob wildcards.
get_metadata(urlpath)
Parameters
urlpath: str, location of data
May be a local path, or remote path if including a protocol
specifier such as 's3://'. May include glob wildcards.
Returns
Metadata (dict) about a given urlpath.
load(urlpath, output=None, **kwargs)
Downloads data from a given url, generates a hashed filename, logs metadata,
and caches it locally.
Parameters
urlpath: str, location of data
May be a local path, or remote path if including a protocol
specifier such as 's3://'. May include glob wildcards.
output: bool
Whether to show progress bars; turn off for testing
Returns
List of local cache_paths to be opened instead of the remote file(s).
If
caching is disable, the urlpath is returned.
class intake.source.base.PatternMixin
Helper class to provide file-name parsing abilities to a driver class
class intake.source.base.Schema(**kwargs)
Holds details of data description for any type of data-source
This should always be pickleable, so that it can be sent from a server to a client,
and contain all information needed to recreate a RemoteSource on the client.
class intake.container.persist.PersistStore(*args, **kwargs)
Specialised catalog for persisted data-sources
add(key, source)
Add the persisted source to the store under the given key
key str The unique token of the un-persisted, original source
source DataSource instance The thing to add to the persisted catalogue,
referring to persisted data
backtrack(source)
Given a unique key in the store, recreate original source
get_tok(source)
Get string token from object
Strings are assumed to already be a token; if source or entry, see if it is
a persisted thing ("original_tok" is in its metadata), else generate its own
token.
needs_refresh(source)
Has the (persisted) source expired in the store
Will return True if the source is not in the store at all, if it's TTL is
set to None, or if more seconds have passed than the TTL.
refresh(key)
Recreate and re-persist the source for the given unique ID
remove(source, delfiles=True)
Remove a dataset from the persist store
source str or DataSource or Lo If a str, this is the unique ID of the
original source, which is the key of the persisted dataset within the
store. If a source, can be either the original or the persisted
source.
delfiles
bool Whether to remove the on-disc artifact
Other Classes
Cache Types
┌────────────────────────────────────────────┬──────────────────────────────────┐
│intake.source.cache.FileCache(driver, │ Cache specific set of files │
│spec) │ │
├────────────────────────────────────────────┼──────────────────────────────────┤
│intake.source.cache.DirCache(driver, │ Cache a complete directory tree │
│spec[, ...]) │ │
├────────────────────────────────────────────┼──────────────────────────────────┤
│intake.source.cache.CompressedCache(driver, │ Cache files extracted from │
│spec) │ downloaded compressed source │
├────────────────────────────────────────────┼──────────────────────────────────┤
│intake.source.cache.DATCache(driver, spec[, │ Use the DAT protocol to │
│...]) │ replicate data │
├────────────────────────────────────────────┼──────────────────────────────────┤
│intake.source.cache.CacheMetadata(*args, │ Utility class for managing │
│...) │ persistent metadata stored in │
│ │ the Intake config directory. │
└────────────────────────────────────────────┴──────────────────────────────────┘
class intake.source.cache.FileCache(driver, spec, catdir=None, cache_dir=None,
storage_options={})
Cache specific set of files
Input is a single file URL, URL with glob characters or list of URLs. Output is a
specific set of local files.
class intake.source.cache.DirCache(driver, spec, catdir=None, cache_dir=None,
storage_options={})
Cache a complete directory tree
Input is a directory root URL, plus a depth parameter for how many levels of
subdirectories to search. All regular files will be copied. Output is the resultant
local directory tree.
class intake.source.cache.CompressedCache(driver, spec, catdir=None, cache_dir=None,
storage_options={})
Cache files extracted from downloaded compressed source
For one or more remote compressed files, downloads to local temporary dir and
extracts all contained files to local cache. Input is URL(s) (including globs)
pointing to remote compressed files, plus optional decomp, which is "infer" by
default (guess from file extension) or one of the key strings in
intake.source.decompress.decomp. Optional regex_filter parameter is used to load
only the extracted files that match the pattern. Output is the list of extracted
files.
class intake.source.cache.DATCache(driver, spec, catdir=None, cache_dir=None,
storage_options={})
Use the DAT protocol to replicate data
For details of the protocol, see https://docs.datproject.org/ The executable dat
must be available.
Since in this case, it is not possible to access the remote files directly, this
cache mechanism takes no parameters. The expectation is that the url passed by the
driver is of the form:
dat://<dat hash>/file_pattern
where the file pattern will typically be a glob string like "*.json".
class intake.source.cache.CacheMetadata(*args, **kwargs)
Utility class for managing persistent metadata stored in the Intake config
directory.
keys() -> a set-like object providing a view on D's keys
pop(k[, d]) -> v, remove specified key and return the corresponding value.
If key is not found, d is returned if given, otherwise KeyError is raised.
update([E], **F) -> None. Update D from mapping/iterable E and F.
If E present and has a .keys() method, does: for k in E: D[k] = E[k] If
E present and lacks .keys() method, does: for (k, v) in E: D[k] = v In
either case, this is followed by: for k, v in F.items(): D[k] = v
Auth
┌────────────────────────────────────────────┬──────────────────────────────────┐
│intake.auth.secret.SecretAuth(*args, │ A very simple auth mechanism │
│**kwargs) │ using a shared secret │
├────────────────────────────────────────────┼──────────────────────────────────┤
│intake.auth.secret.SecretClientAuth(secret) │ Matching client auth plugin to │
│ │ SecretAuth │
└────────────────────────────────────────────┴──────────────────────────────────┘
class intake.auth.secret.SecretAuth(*args, **kwargs)
A very simple auth mechanism using a shared secret
Parameters
secret: str
The string that must be matched in the requests. If None, a random
UUID is generated and logged.
key: str
Header entry in which to seek the secret
allow_access(header, source, catalog)
Is the given HTTP header allowed to access given data source
Parameters
header: dict
The HTTP header from the incoming request
source: CatalogEntry
The data source the user wants to access.
catalog: Catalog
The catalog object containing this data source.
allow_connect(header)
Is the requests header given allowed to talk to the server
Parameters
header: dict
The HTTP header from the incoming request
class intake.auth.secret.SecretClientAuth(secret, key='intake-secret')
Matching client auth plugin to SecretAuth
Parameters
secret: str
The string that must be included requests.
key: str
HTTP Header key for the shared secret
get_headers()
Returns a dictionary of HTTP headers for the remote catalog request.
Containers
┌──────────────────────────────────────────────────────────┬──────────────────────────────────┐
│intake.container.dataframe.RemoteDataFrame(...) │ Dataframe on an Intake server │
├──────────────────────────────────────────────────────────┼──────────────────────────────────┤
│intake.container.ndarray.RemoteArray(*args, │ nd-array on an Intake server │
│...) │ │
└──────────────────────────────────────────────────────────┴──────────────────────────────────┘
│intake.container.semistructured.RemoteSequenceSource(...) │ Sequence-of-things source on an │
│ │ Intake server │
└──────────────────────────────────────────────────────────┴──────────────────────────────────┘
class intake.container.dataframe.RemoteDataFrame(*args, **kwargs)
Dataframe on an Intake server
read() Load entire dataset into a container and return it
to_dask()
Return a dask container for this data source
class intake.container.ndarray.RemoteArray(*args, **kwargs)
nd-array on an Intake server
read() Load entire dataset into a container and return it
read_partition(i)
Return a part of the data corresponding to i-th partition.
By default, assumes i should be an integer between zero and npartitions;
override for more complex indexing schemes.
to_dask()
Return a dask container for this data source
class intake.container.semistructured.RemoteSequenceSource(*args, **kwargs)
Sequence-of-things source on an Intake server
read() Load entire dataset into a container and return it
to_dask()
Return a dask container for this data source
Server
┌──────────────────────────────────────────────────┬──────────────────────────────────┐
│intake.cli.server.server.IntakeServer(catalog) │ Main intake-server tornado │
│ │ application │
├──────────────────────────────────────────────────┼──────────────────────────────────┤
│intake.cli.server.server.ServerInfoHandler(...) │ Basic info about the server │
├──────────────────────────────────────────────────┼──────────────────────────────────┤
│intake.cli.server.server.SourceCache() │ Stores DataSources requested by │
│ │ some user │
├──────────────────────────────────────────────────┼──────────────────────────────────┤
│intake.cli.server.server.ServerSourceHandler(...) │ Open or stream data source │
└──────────────────────────────────────────────────┴──────────────────────────────────┘
class intake.cli.server.server.IntakeServer(catalog)
Main intake-server tornado application
class intake.cli.server.server.ServerInfoHandler(application: tornado.web.Application,
request: tornado.httputil.HTTPServerRequest, **kwargs: Any)
Basic info about the server
class intake.cli.server.server.SourceCache
Stores DataSources requested by some user
peek(uuid)
Get the source but do not change the last access time
class intake.cli.server.server.ServerSourceHandler(application: tornado.web.Application,
request: tornado.httputil.HTTPServerRequest, **kwargs: Any)
Open or stream data source
The requests "action" field (open|read) specified what the request wants to do.
Open caches the source and created an ID for it, read uses that ID to reference the
source and read a partition.
get() Access one source's info.
This is for direct access to an entry by name for random access, which is
useful to the client when the whole catalog has not first been listed and
pulled locally (e.g., in the case of pagination).
GUI
Making Drivers
The goal of the Intake plugin system is to make it very simple to implement a Driver for a
new data source, without any special knowledge of Dask or the Intake catalog system.
Assumptions
Although Intake is very flexible about data, there are some basic assumptions that a
driver must satisfy.
Data Model
Intake currently supports 3 kinds of containers, represented the most common data models
used in Python:
• dataframe
• ndarray
• python (list of Python objects, usually dictionaries)
Although a driver can load any type of data into any container, and new container types
can be added to the list above, it is reasonable to expect that the number of container
types remains small. Declaring a container type is only informational for the user when
read locally, but streaming of data from a server requires that the container type be
known to both server and client.
A given driver must only return one kind of container. If a file format (such as HDF5)
could reasonably be interpreted as two different data models depending on usage (such as a
dataframe or an ndarray), then two different drivers need to be created with different
names. If a driver returns the python container, it should document what Python objects
will appear in the list.
The source of data should be essentially permanent and immutable. That is, loading the
data should not destroy or modify the data, nor should closing the data source destroy the
data either. When a data source is serialized and sent to another host, it will need to
be reopened at the destination, which may cause queries to be re-executed and files to be
reopened. Data sources that treat readers as "consumers" and remove data once read will
cause erratic behavior, so Intake is not suitable for accessing things like FIFO message
queues.
Schema
The schema of a data source is a detailed description of the data, which can be known by
loading only metadata or by loading only some small representative portion of the data. It
is information to present to the user about the data that they are considering loading,
and may be important in the case of server-client communication. In the latter context,
the contents of the schema must be serializable by msgpack (i.e., numbers, strings, lists
and dictionaries only).
There may be unknown parts of the schema before the whole data is read. drivers may
require this unknown information in the __init__() method (or the catalog spec), or do
some kind of partial data inspection to determine the schema; or more simply, may be given
as unknown None values. Regardless of method used, the time spent figuring out the schema
ahead of time should be short and not scale with the size of the data.
Typical fields in a schema dictionary are npartitions, dtype, shape, etc., which will be
more appropriate for some drivers/data-types than others.
Partitioning
Data sources are assumed to be partitionable. A data partition is a randomly accessible
fragment of the data. In the case of sequential and data-frame sources, partitions are
numbered, starting from zero, and correspond to contiguous chunks of data divided along
the first dimension of the data structure. In general, any partitioning scheme is
conceivable, such as a tuple-of-ints to index the chunks of a large numerical array.
Not all data sources can be partitioned. For example, file formats without sufficient
indexing often can only be read from beginning to end. In these cases, the DataSource
object should report that there is only 1 partition. However, it often makes sense for a
data source to be able to represent a directory of files, in which case each file will
correspond to one partition.
Metadata
Once opened, a DataSource object can have arbitrary metadata associated with it. The
metadata for a data source should be a dictionary that can be serialized as JSON. This
metadata comes from the following sources:
1. A data catalog entry can associate fixed metadata with the data source. This is
helpful for data formats that do not have any support for metadata within the file
format.
2. The driver handling the data source may have some general metadata associated with the
state of the system at the time of access, available even before loading any
data-specific information.
2. A driver can add additional metadata when the schema is loaded for the data source.
This allows metadata embedded in the data source to be exported.
From the user perspective, all of the metadata should be loaded once the data source has
loaded the rest of the schema (after discover(), read(), to_dask(), etc have been called).
Subclassing intake.source.base.DataSourceBase
Every Intake driver class should be a subclass of intake.source.base.DataSource. The
class should have the following attributes to identify itself:
• name: The short name of the driver. This should be a valid python identifier. You
should not include the word intake in the driver name.
• version: A version string for the driver. This may be reported to the user by tools
based on Intake, but has no semantic importance.
• container: The container type of data sources created by this object, e.g., dataframe,
ndarray, or python, one of the keys of intake.container.container_map. For simplicity,
a driver many only return one typed of container. If a particular source of data could
be used in multiple ways (such as HDF5 files interpreted as dataframes or as ndarrays),
two drivers must be created. These two drivers can be part of the same Python package.
• partition_access: Do the data sources returned by this driver have multiple partitions?
This may help tools in the future make more optimal decisions about how to present data.
If in doubt (or the answer depends on init arguments), True will always result in
correct behavior, even if the data source has only one partition.
The __init()__ method should always accept a keyword argument metadata, a dictionary of
metadata from the catalog to associate with the source. This dictionary must be
serializable as JSON.
The DataSourceBase class has a small number of methods which should be overridden. Here
is an example producing a data-frame:
class FooSource(intake.source.base.DataSource):
container = 'dataframe'
name = 'foo'
version = '0.0.1'
partition_access = True
def __init__(self, a, b, metadata=None):
# Do init here with a and b
super(FooSource, self).__init__(
metadata=metadata
)
def _get_schema(self):
return intake.source.base.Schema(
datashape=None,
dtype={'x': "int64", 'y': "int64"},
shape=(None, 2),
npartitions=2,
extra_metadata=dict(c=3, d=4)
)
def _get_partition(self, i):
# Return the appropriate container of data here
return pd.DataFrame({'x': [1, 2, 3], 'y': [10, 20, 30]})
def read(self):
self._load_metadata()
return pd.concat([self.read_partition(i) for i in range(self.npartitions)])
def _close(self):
# close any files, sockets, etc
pass
Most of the work typically happens in the following methods:
• __init__(): Should be very lightweight and fast. No files or network resources should
be opened, and no significant memory should be allocated yet. Data sources might be
serialized immediately. The default implementation of the pickle protocol in the base
class will record all the arguments to __init__() and recreate the object with those
arguments when unpickled, assuming the class has no side effects.
• _get_schema(): May open files and network resources and return as much of the schema as
possible in small amount of approximately constant time. Typically, imports of packages
needed by the source only happen here. The npartitions and extra_metadata attributes
must be correct when _get_schema returns. Further keys such as dtype, shape, etc.,
should reflect the container type of the data-source, and can be None if not easily
knowable, or include None for some elements. File-based sources should use fsspec to
open a local or remote URL, and pass storage_options to it. This ensures compatibility
and extra features such as caching. If the backend can only deal with local files, you
may still want to use fsspec.open_local to allow for caching.
• _get_partition(self, i): Should return all of the data from partition id i, where i is
typically an integer, but may be something more complex. The base class will
automatically verify that i is in the range [0, npartitions), so no range checking is
required in the typical case.
• _close(self): Close any network or file handles and deallocate any significant memory.
Note that these resources may be need to be reopened/reallocated if a read is called
again later.
The full set of user methods of interest are as follows:
• discover(self): Read the source attributes, like npartitions, etc. As with
_get_schema() above, this method is assumed to be fast, and make a best effort to set
attributes. The output should be serializable, if the source is to be used on a server;
the details contained will be used for creating a remote-source on the client.
• read(self): Return all the data in memory in one in-memory container.
• read_chunked(self): Return an iterator that returns contiguous chunks of the data. The
chunking is generally assumed to be at the partition level, but could be finer grained
if desired.
• read_partition(self, i): Returns the data for a given partition id. It is assumed that
reading a given partition does not require reading the data that precedes it. If i is
out of range, an IndexError should be raised.
• to_dask(self): Return a (lazy) Dask data structure corresponding to this data source.
It should be assumed that the data can be read from the Dask workers, so the loads can
be done in future tasks. For further information, see the Dask documentation.
• close(self): Close network or file handles and deallocate memory. If other methods are
called after close(), the source is automatically reopened.
• to_*: for some sources, it makes sense to provide alternative outputs aside from the
base container (dataframe, array, ...) and Dask variants.
Note that all of these methods typically call _get_schema, to make sure that the source
has been initialised.
Subclassing intake.source.base.DataSource
DataSource provides the same functionality as DataSourceBase, but has some additional
mixin classes to provide some extras. A developer may choose to derive from DataSource to
get all of these, or from DataSourceBase and make their own choice of mixins to support.
• HoloviewsMixin: provides plotting and GUI capabilities via the holoviz stack
• PersistMixin: allows for storing a local copy in a default format for the given
container type
• CacheMixin: allows for local storage of data files for a source. Deprecated, you should
use one of the caching mechanisms in fsspec.
Driver Discovery
Intake discovers available drivers in three different ways, described below. After the
discovery phase, Intake will automatically create open_[driver_name] convenience functions
under the intake module namespace. Calling a function like open_csv() is equivalent to
instantiating the corresponding data-source class.
Entrypoints
If you are packaging your driver into an installable package to be shared, you should add
the following to the package's setup.py:
setup(
...
entry_points={
'intake.drivers': [
'some_format_name = some_package.and_maybe_a_submodule:YourDriverClass',
...
]
},
)
IMPORTANT:
Some critical details of Python's entrypoints feature:
• Note the unusual syntax of the entrypoints. Each item is given as one long string,
with the = as part of the string. Modules are separated by ., and the final object
name is preceded by :.
• The right hand side of the equals sign must point to where the object is actually
defined. If YourDriverClass is defined in foo/bar.py and imported into
foo/__init__.py you might expect foo:YourDriverClass to work, but it does not. You
must spell out foo.bar:YourDriverClass.
Entry points are a way for Python packages to advertise objects with some common
interface. When Intake is imported, it discovers all packages installed in the current
environment that advertise 'intake.drivers' in this way.
Most packages that define intake drivers have a dependency on intake itself, for example
in order to use intake's base classes. This can create a circular dependency: importing
the package imports intake, which tries to discover and import packages that define
drivers. To avoid this pitfall, just ensure that intake is imported first thing in your
package's __init__.py. This ensures that the driver-discovery code runs first. Note that
you are not required to make your package depend on intake. The rule is that if you import
intake you must import it first thing. If you do not import intake, there is no
circularity.
Configuration
The intake configuration file can be used to:
• Specify precedence in the event of name collisions---for example, if two different csv
drivers are installed.
• Disable a troublesome driver.
• Manually make intake aware of a driver, which can be useful for experimentation and
early development until a setup.py with an entrypoint is prepared.
• Assign a driver to a name other than the one assigned by the driver's author.
The commandline invocation
intake drivers enable some_format_name some_package.and_maybe_a_submodule.YourDriverClass
is equivalent to adding this to your intake configuration file:
drivers:
some_format_name: some_package.and_maybe_a_submodule.YourDriverClass
You can also disable a troublesome driver
intake drivers disable some_format_name
which is equivalent to
drivers:
your_format_name: false
Deprecated: Package Scan
When Intake is imported, it will search the Python module path (by default includes
site-packages and other directories in your $PYTHONPATH) for packages starting with
intake\_ and discover DataSource subclasses inside those packages to register. drivers
will be registered based on the``name`` attribute of the object. By convention, drivers
should have names that are lowercase, valid Python identifiers that do not contain the
word intake.
This approach is deprecated because it is limiting (requires the package to begin with
"intake_") and because the package scan can be slow. Using entrypoints is strongly
encouraged. The package scan may be disabled by default in some future release of intake.
During the transition period, if a package named intake_* provides an entrypoint for a
given name, that will take precedence over any drivers gleaned from the package scan
having that name. If intake discovers any names from the package scan for which there are
no entrypoints, it will issue a FutureWarning.
Python API to Driver Discovery
intake.source.discovery.autodiscover(path=None, plugin_prefix='intake_',
do_package_scan=False)
Discover intake drivers.
In order of decreasing precedence:
• Respect the 'drivers' section of the intake configuration file.
• Find 'intake.drivers' entrypoints provided by any Python packages in the
environment.
• Search all packages in the environment for names that begin with intake\_. Import
them and scan them for subclasses of intake.source.base.DataSourceBase. This was
previously the only mechanism for auto-discoverying intake drivers, and it is
maintained for backward compatibility.
Parameters
path str or None Default is sys.path.
plugin_prefix
str DEPRECATED. Default is 'intake_'.
do_package_scan
boolean Whether to look for intake source classes in packages named
"intake_*". This has been superseded by entrypoints declarations.
Returns
drivers
dict Name mapped to driver class.
intake.source.discovery.enable(name, driver)
Update config file drivers section to explicitly assign a driver to a name.
Parameters
name string As in 'zarr'
driver string Dotted object name, as in 'intake_xarray.xzarr.ZarrSource'
intake.source.discovery.disable(name)
Update config file drivers section to disable a name.
Parameters
name string As in 'zarr'
Remote Data
For drivers loading from files, the author should be aware that it is easy to implement
loading from files stored in remote services. A simplistic case is demonstrated by the
included CSV driver, which simply passes a URL to Dask, which in turn can interpret the
URL as a remote data service, and use the storage_options as required (see the Dask
documentation on remote data).
More advanced usage, where a Dask loader does not already exist, will likely rely on
fsspec.open_files . Use this function to produce lazy OpenFile object for local or remote
data, based on a URL, which will have a protocol designation and possibly contain glob "*"
characters. Additional parameters may be passed to open_files, which should, by
convention, be supplied by a driver argument named storage_options (a dictionary).
To use an OpenFile object, make it concrete by using a context:
# at setup, to discover the number of files/partitions
set_of_open_files = fsspec.open_files(urlpath, mode='rb', **storage_options)
# when actually loading data; here we loop over all files, but maybe we just do one partition
for an_open_file in set_of_open_files:
# `with` causes the object to become concrete until the end of the block
with an_open_file as f:
# do things with f, which is a file-like object
f.seek(); f.read()
The textfiles builtin drivers implements this mechanism, as an example.
Structured File Paths
The CSV driver sets up an example of how to gather data which is encoded in file paths
like ('data_{site}_.csv') and return that data in the output. Other drivers could also
follow the same structure where data is being loaded from a set of filenames. Typically
this would apply to data-frame output. This is possible as long as the driver has access
to each of the file paths at some point in _get_schema. Once the file paths are known, the
driver developer can use the helper functions defined in intake.source.utils to get the
values for each field in the pattern for each file in the list. These values should then
be added to the data, a process which normally would happen within the _get_schema method.
The PatternMixin defines driver properties such as urlpath, path_as_pattern, and pattern.
The implementation might look something like this:
from intake.source.utils import reverse_formats
class FooSource(intake.source.base.DataSource, intake.source.base.PatternMixin):
def __init__(self, a, b, path_as_pattern, urlpath, metadata=None):
# Do init here with a and b
self.path_as_pattern = path_as_pattern
self.urlpath = urlpath
super(FooSource, self).__init__(
container='dataframe',
metadata=metadata
)
def _get_schema(self):
# read in the data
values_by_field = reverse_formats(self.pattern, file_paths)
# add these fields and map values to the data
return data
Since dask already has a specific method for including the file paths in the output
dataframe, in the CSV driver we set include_path_column=True, to get a dataframe where one
of the columns contains all the file paths. In this case, add these fields and values to
data is a mapping between the categorical file paths column and the values_by_field.
In other drivers where each file is read in independently the driver developer can set the
new fields on the data from each file before concattenating. This pattern looks more
like:
from intake.source.utils import reverse_format
class FooSource(intake.source.base.DataSource):
...
def _get_schema(self):
# get list of file paths
for path in file_paths:
# read in the file
values_by_field = reverse_format(self.pattern, path)
# add these fields and values to the data
# concatenate the datasets
return data
To toggle on and off this path as pattern behavior, the CSV and intake-xarray drivers uses
the bool path_as_pattern keyword argument.
Authorization Plugins
Authorization plugins are classes that can be used to customize access permissions to the
Intake catalog server. The Intake server and client communicate over HTTP, so when
security is a concern, the most important step to take is to put a TLS-enabled reverse
proxy (like nginx) in front of the Intake server to encrypt all communication.
Whether or not the connection is encrypted, the Intake server by default allows all
clients to list the full catalog, and open any of the entries. For many use cases, this
is sufficient, but if the visibility of catalog entries needs to be limited based on some
criteria, a server- (and/or client-) side authorization plugin can be used.
Server Side
An Intake server can have exactly one server side plugin enabled at startup. The plugin
is activated using the Intake configuration file, which lists the class name and the
keyword arguments it takes. For example, the "shared secret" plugin would be configured
this way:
auth:
cls: intake.auth.secret.SecretAuth
kwargs:
secret: A_SECRET_HASH
This plugin is very simplistic, and exists as a demonstration of how an auth plugin might
function for more realistic scenarios.
For more information about configuring the Intake server, see configuration.
The server auth plugin has two methods. The allow_connect() method decides whether to
allow a client to make any request to the server at all, and the allow_access() method
decides whether the client is allowed to see a particular catalog entry in the listing and
whether they are allowed to open that data source. Note that for catalog entries which
allow direct access to the data (via network or shared filesystem), the Intake
authorization plugins have no impact on the visibility of the underlying data, only the
entries in the catalog.
The actual implementation of a plugin is very short. Here is a simplified version of the
shared secret auth plugin:
class SecretAuth(BaseAuth):
def __init__(self, secret, key='intake-secret'):
self.secret = secret
self.key = key
def allow_connect(self, header):
try:
return self.get_case_insensitive(header, self.key, '') \
== self.secret
except:
return False
def allow_access(self, header, source, catalog):
try:
return self.get_case_insensitive(header, self.key, '') \
== self.secret
except:
return False
The header argument is a dictionary of HTTP headers that were present in the client
request. In this case, the plugin is looking for a special intake-secret header which
contains the shared secret token. Because HTTP header names are not case sensitive, the
BaseAuth class provides a helper method get_case_insensitive(), which will match
dictionary keys in a case-insensitive way.
The allow_access method also takes two additional arguments. The source argument is the
instance of LocalCatalogEntry for the data source being checked. Most commonly auth
plugins will want to inspect the _metadata dictionary for information used to make the
authorization decision. Note that it is entirely up to the plugin author to decide what
sections they want to require in the metadata section. The catalog argument is the
instance of Catalog that contains the catalog entry. Typically, plugins will want to use
information from the catalog.metadata dictionary to control global defaults, although this
is also up to the plugin.
Client Side
Although server side auth plugins can function entirely independently, some authorization
schemes will require the client to add special HTTP headers for the server to look for.
To facilitate this, the Catalog constructor accepts an optional auth parameter with an
instance of a client auth plugin class.
The corresponding client plugin for the shared secret use case describe above looks like:
class SecretClientAuth(BaseClientAuth):
def __init__(self, secret, key='intake-secret'):
self.secret = secret
self.key = key
def get_headers(self):
return {self.key: self.secret}
It defines a single method, get_headers(), which is called to get a dictionary of
additional headers to add to the HTTP request to the catalog server. To use this plugin,
we would do the following:
import intake
from intake.auth.secret import SecretClientAuth
auth = SecretClientAuth('A_SECRET_HASH')
cat = intake.Catalog('http://example.com:5000', auth=auth)
Now all requests made to the remote catalog will contain the intake-secret header.
Making Data Packages
Intake can used to create Data packages, so that you can easily distribute your catalogs -
others can just "install data". Since you may also want to distribute custom catalogues,
perhaps with visualisations, and driver code, packaging these things together is a great
convenience. Indeed, packaging gives you the opportunity to version-tag your distribution
and to declare the requirements needed to be able to use the data. This is a common
pattern for distributing code for python and other languages, but not commonly seen for
data artifacts.
The current version of Intake allows making data packages using standard python tools (to
be installed, for example, using pip). The previous, now deprecated, technique is still
described below, under Pure conda solution and is specific to the conda packaging system.
Python packaging solution
Intake allows you to register data artifacts (catalogs and data sources) in the metadata
of a python package. This means, that when you install that package, intake will
automatically know of the registered items, and they will appear within the "builtin"
catalog intake.cat.
Here we assume that you understand what is meant by a python package (i.e., a folder
containing __init__.py and other code, config and data files). Furthermore, you should
familiarise yourself with what is required for bundling such a package into a
distributable package (one with a setup.py) by reading the official packaging
documentation
The intake examples contains a full tutorial for packaging and distributing intake data
and/or catalogs for pip and conda, see the directory "data_package/".
Entry points definition
Intake uses the concept of entry points to define the entries that are defined by a given
package. Entry points provide a mechanism to register metadata about a package at install
time, so that it can easily be found by other packages such as Intake. Entry points was
originally a separate package, but is included in the standard library as of python 3.8
(you will not need to install it, as Intake requires it).
All you need to do to register an entry in intake.cat is:
• define a data source somewhere in your package. This object can be of any ttype that
makes sense to Intake, including Catalogs, and sources that have drivers defined in the
very same package. Obviously, if you can have catalogs, you can populate these however
you wish, including with more catalogs. You need not be restricted to simply loading in
YAML files.
• include a block in your call to setp in setup.py with code something like
entry_points={
'intake.catalogs': [
'sea_cat = intake_example_package:cat',
'sea_data = intake_example_package:data'
]
}
Here only the lines with "sea_cat" and "sea_data" are specific to the example
package, the rest is required boilerplate. Each of those two lines defines a name
for the data entry (before the "=" sign) and the location to load from, in
module:object format.
• install the package using pip, python setup.py, or package it for conda
Intake's process
When Intake is imported, it investigates all registered entry points with the
"intake.catalogs" group. It will go through and assign each name to the given location of
the final object. In the above example, intake.cat.sea_cat would be associated with the
cat object in the intake_example_package package, and so on.
Note that Intake does not immediately import the given package or module, because imports
can sometimes be expensive, and if you have a lot of data packages, it might cause a
slow-down every time that Intake is imported. Instead, a placeholder entry is created, and
whenever the entry is accessed, that's when the particular package will be imported.
In [1]: import intake
In [2]: intake.cat.sea_cat # does not import yet
Out[2]: <Entry containing Catalog named sea_cat>
In [3]: cat = intake.cat.sea_cat() # imports now
In [4]: cat # this data source happens to be a catalog
Out[4]: <Intake catalog: sea>
(note here the parentheses - this explicitly initialises the source, and normally you
don't have to do this)
Pure conda solution
This packaging method is deprecated, but still available.
Combined with the Conda Package Manger, Intake makes it possible to create Data packages
which can be installed and upgraded just like software packages. This offers several
advantages:
• Distributing Catalogs and Drivers becomes as easy as conda install
• Data packages can be versioned, improving reproducibility in some cases
• Data packages can depend on the libraries required for reading
• Data packages can be self-describing using Intake catalog files
• Applications that need certain Catalogs can include data packages in their dependency
list
In this tutorial, we give a walk-through to enable you to distribute any Catalogs to
others, so that they can access the data using Intake without worrying about where it
resides or how it should be loaded.
Implementation
The function intake.catalog.default.load_combo_catalog searches for YAML catalog files in
a number of place at import. All entries in these catalogs are flattened and placed in the
"builtin" intake.cat.
The places searched are:
• a platform-specific user directory as given by the appdirs package
• in the environment's "/share/intake" data directory, where the location of the
current environment is found from virtualenv or conda environment variables
• in directories listed in the "INTAKE_PATH" environment variable or "catalog_path"
config parameter
Defining a Package
The steps involved in creating a data package are:
1. Identifying a dataset, which can be accessed via a URL or included directly as one or
more files in the package.
2. Creating a package containing:
• an intake catalog file
• a meta.yaml file (description of the data, version, requirements, etc.)
• a script to copy the data
3. Building the package using the command conda build.
4. Uploading the package to a package repository such as Anaconda Cloud or your own
private repository.
Data packages are standard conda packages that install an Intake catalog file into the
user's conda environment ($CONDA_PREFIX/share/intake). A data package does not
necessarily imply there are data files inside the package. A data package could describe
remote data sources (such as files in S3) and take up very little space on disk.
These packages are considered noarch packages, so that one package can be installed on any
platform, with any version of Python (or no Python at all). The easiest way to create
such a package is using a conda build recipe.
Conda-build recipes are stored in a directory that contains a files like:
• meta.yaml - description of package metadata
• build.sh - script for building/installing package contents (on Linux/macOS)
• other files needed by the package (catalog files and data files for data packages)
An example that packages up data from a Github repository would look like this:
# meta.yaml
package:
version: '1.0.0'
name: 'data-us-states'
source:
git_rev: v1.0.0
git_url: https://github.com/CivilServiceUSA/us-states
build:
number: 0
noarch: generic
requirements:
run:
- intake
build: []
about:
description: Data about US states from CivilServices (https://civil.services/)
license: MIT
license_family: MIT
summary: Data about US states from CivilServices
The key parts of a data package recipe (different from typical conda recipes) is the build
section:
build:
number: 0
noarch: generic
This will create a package that can be installed on any platform, regardless of the
platform where the package is built. If you need to rebuild a package, the build number
can be incremented to ensure users get the latest version when they conda update.
The corresponding build.sh file in the recipe looks like this:
#!/bin/bash
mkdir -p $CONDA_PREFIX/share/intake/civilservices
cp $SRC_DIR/data/states.csv $PREFIX/share/intake/civilservices
cp $RECIPE_DIR/us_states.yaml $PREFIX/share/intake/
The $SRC_DIR variable refers to any source tree checked out (from Github or other
service), and the $RECIPE_DIR refers to the directory where the meta.yaml is located.
Finishing out this example, the catalog file for this data source looks like this:
sources:
states:
description: US state information from [CivilServices](https://civil.services/)
driver: csv
args:
urlpath: '{{ CATALOG_DIR }}/civilservices/states.csv'
metadata:
origin_url: 'https://github.com/CivilServiceUSA/us-states/blob/v1.0.0/data/states.csv'
The {{ CATALOG_DIR }} Jinja2 variable is used to construct a path relative to where the
catalog file was installed.
To build the package, you must have conda-build installed:
conda install conda-build
Building the package requires no special arguments:
conda build my_recipe_dir
Conda-build will display the path of the built package, which you will need to upload it.
If you want your data package to be publicly available on Anaconda Cloud, you can install
the anaconda-client utility:
conda install anaconda-client
Then you can register your Anaconda Cloud credentials and upload the package:
anaconda login
anaconda upload /Users/intake_user/anaconda/conda-bld/noarch/data-us-states-1.0.0-0.tar.bz2
Best Practices
Versioning
• Versions for data packages should be used to indicate changes in the data values or
schema. This allows applications to easily pin to the specific data version they depend
on.
• Putting data files into a package ensures reproducibility by allowing a version number
to be associated with files on disk. This can consume quite a bit of disk space for the
user, however. Large data files are not generally included in pip or conda packages so,
if possible, you should reference the data assets in an external place where they can be
loaded.
Packaging
• Packages that refer to remote data sources (such as databases and REST APIs) need to
think about authentication. Do not include authentication credentials inside a data
package. They should be obtained from the environment.
• Data packages should depend on the Intake plugins required to read the data, or Intake
itself.
• You may well want to break any driver code code out into a separate package so that it
can be updated independent of the data. The data package would then depend on the driver
package.
Nested catalogs
As noted above, entries will appear in the users' builtin catalog as intake.cat.*. In the
case that the catalog has multiple entries, it may be desirable to put the entries below a
namespace as intake.cat.data_package.*. This can be achieved by having one catalog
containing the (several) data sources, with only a single top-level entry pointing to it.
This catalog could be defined in a YAML file, created using any other catalog driver, or
constructed in the code, e.g.:
from intake.catalog import Catalog
from intake.catalog.local import LocalCatalogEntry as Entry
cat = intake.catalog.Catalog()
cat._entries = {name: Entry(name, descr, driver='package.module.driver',
args={"urlpath": url})
for name, url in my_input_list}
If your package contains many sources of different types, you may even nest the catalogs,
i.e., have a top-level whose contents are also catalogs.
e = Entry('first_cat', 'sample', driver='catalog')
e._default_source = cat
top_level = Catalog()
top_level._entries = {'fist_cat': e, ...}
where your entry point might look something like: "my_cat = my_package:top_level". You
could achieve the same with multiple YAML files.
ROADMAP
Some high-level work that we expect to be achieved on the time-scale of months. This list
is not exhaustive, but rather aims to whet the appetite for what Intake can be in the
future.
Since Intake aims to be a community of data-oriented pythoneers, nothing written here is
laid in stone, and users and devs are encouraged to make their opinions known!
Broaden the coverage of formats
Data-type drivers are easy to write, but still require some effort, and therefore
reasonable impetus to get the work done. Conversations over the coming months can help
determine the drivers that should be created by the Intake team, and those that might be
contributed by the community.
The next type that we would specifically like to consider is machine learning model
artifacts. EDIT see https://github.com/AlbertDeFusco/intake-sklearn , and hopefully more
to come.
Streaming Source
Many data sources are inherently time-sensitive and event-wise. These are not covered well
by existing Python tools, but the streamz library may present a nice way to model them.
From the Intake point of view, the task would be to develop a streaming type, and at least
one data driver that uses it.
The most obvious place to start would be read a file: every time a new line appears in the
file, an event is emitted. This is appropriate, for instance, for watching the log files
of a web-server, and indeed could be extended to read from an arbitrary socket.
EDIT see: https://github.com/intake/intake-streamz
Server publish hooks
To add API endpoints to the server, so that a user (with sufficient privilege) can post
data specifications to a running server, optionally saving the specs to a catalog
server-side. Furthermore, we will consider the possibility of being able to upload and/or
transform data (rather than refer to it in a third-party location), so that you would have
a one-line "publish" ability from the client.
The server, in general, could do with a lot of work to become more than the current
demonstration/prototype. In particular, it should be able to be performant and scalable,
meaning that the server implementation ought to keep as little local state as possible.
Simplify dependencies and class hierarchy
We would like the make it easier to write Intake drivers which don't need any persist or
GUI functionality, and to be able to install Intake core functionality (driver registry,
data loading and catalog traversal) without needing many other packages at all.
EDIT this has been partly done, you can derive from DataSourceBase and not have to use the
full set of Intake's features for simplicity. We have also gone some distance to separate
out dependencies for parts of the package, so that you can install Intake and only use
some of the subpackages/modules - imports don't happen until those parts of the code are
used. We have not yet split the intake conda package into, for example, intake-base,
intake-server, intake-gui...
Reader API
For those that wish to provide Intake's data source API, and make data sources available
to Intake cataloguing, but don't wish to take Intake as a direct dependency. The actual
API of DataSources is rather simple:
• __init__: collect arguments, minimal IO at this point
• discover(): get metadata from the source, by querying the files/service itself
• read(): return in-memory version of the data
• to_*: return reference objects for the given compute engine, typically Dask
• read_partition(...): read part of the data into memory, where the argument makes sense
for the given type of data
• configure_new(): create new instance with different arguments
• yaml(): representation appropriate for inclusion in a YAML catalogue
• close(): release any resources
Of these, only the first three are really necessary for a iminal interface, so Intake
might do well to publish this protocol specification, so that new drivers can be written
that can be used by Intake but do not need Intake, and so help adoption.
GLOSSARY
Argument
One of a set of values passed to a function or class. In the Intake sense, this
usually is the set of key-value pairs defined in the "args" section of a source
definition; unless the user overrides, these will be used for instantiating the
source.
Cache Local copies of remote files. Intake allows for download-on-first-use for
data-sources, so that subsequent access is much faster, see caching. The format of
the files is unchanged in this case, but may be decompressed.
Catalog
A collection of entries, each of which corresponds to a specific Data-set. Within
these docs, a catalog is most commonly defined in a YAML file, for simplicity, but
there are other possibilities, such as connecting to an Intake server or another
third-party data service, like a SQL database. Thus, catalogs form a hierarchy: any
catalog can contain other, nested catalogs.
Catalog file
A YAML specification file which contains a list of named entries describing how to
load data sources. catalog.
Conda A package and environment management package for the python ecosystem, see the
conda website. Conda ensures dependencies and correct versions are installed for
you, provides precompiled, binary-compatible software, and extends to many
languages beyond python, such as R, javascript and C.
Conda package
A single installable item which the Conda application can install. A package may
include a Catalog, data-files and maybe some additional code. It will also include
a specification of the dependencies that it requires (e.g., Intake and any
additional Driver), so that Conda can install those automatically. Packages can be
created locally, or can be found on anaconda.org or other package repositories.
Container
One of the supported data formats. Each Driver outputs its data in one of these.
The containers correspond to familiar data structures for end-analysis, such as
list-of-dicts, Numpy nd-array or Pandas data-frame.
Data-set
A specific collection of data. The type of data (tabular, multi-dimensional or
something else) and the format (file type, data service type) are all attributes of
the data-set. In addition, in the context of Intake, data-sets are usually entries
within a Catalog with additional descriptive text and metadata and a specification
of how to load the data.
Data Source
An Intake specification for a specific Data-set. In most cases, the two terms are
synonymous.
Data User
A person who uses data to produce models and other inferences/conclusions. This
person generally uses standard python analysis packages like Numpy, Pandas, SKLearn
and may produce graphical output. They will want to be able to find the right data
for a given job, and for the data to be available in a standard format as quickly
and easily as possible. In many organisations, the appropriate job title may be
Data Scientist, but research scientists and BI/analysts also fit this description.
Data packages
Data packages are standard conda packages that install an Intake catalog file into
the user’s conda environment ($CONDA_PREFIX/share/intake). A data package does not
necessarily imply there are data files inside the package. A data package could
describe remote data sources (such as files in S3) and take up very little space on
disk.
Data Provider
A person whose main objective is to curate data sources, get them into appropriate
formats, describe the contents, and disseminate the data to those that need to use
them. Such a person may care about the specifics of the storage format and backing
store, the right number of fields to keep and removing bad data. They may have a
good idea of the best way to visualise any give data-set. In an organisation, this
job may be known as Data Engineer, but it could as easily be done by a member of
the IT team. These people are the most likely to author Catalogs.
Developer
A person who writes or fixes code. In the context of Intake, a developer may make
new format Drivers, create authentication systems or add functionality to Intake
itself. They can take existing code for loading data in other projects, and use
Intake to add extra functionality to it, for instance, remote data access, parallel
processing, or file-name parsing.
Driver The thing that does the work of reading the data for a catalog entry is known as a
driver, often referred to using a simple name such as "csv". Intake has a plugin
architecture, and new drivers can be created or installed, and specific
catalogs/data-sets may require particular drivers for their contained data-sets. If
installed as Conda packages, then these requirements will be automatically
installed for you. The driver's output will be a Container, and often the code is a
simpler layer over existing functionality in a third-party package.
GUI A Graphical User Interface. Intake comes with a GUI for finding and selecting
data-sets, see gui.
IT The Information Technology team for an organisation. Such a team may have control
of the computing infrastructure and security (sys-ops), and may well act as
gate-keepers when exposing data for use by other colleagues. Commonly, IT has
stronger policy enforcement requirements that other groups, for instance requiring
all data-set copy actions to be logged centrally.
Persist
A process of making a local version of a data-source. One canonical format is used
for each of the container types, optimised for quick and parallel access. This is
particularly useful if the data takes a long time to acquire, perhaps because it is
the result of a complex query on a remote service. The resultant output can be set
to expire and be automatically refreshed, see persisting. Not to be confused with
the cache.
Plugin Modular extra functionality for Intake, provided by a package that is installed
separately. The most common type of plugin will be for a Driver to load some
particular data format; but other parts of Intake are pluggable, such as
authentication mechanisms for the server.
Server A remote source for Intake catalogs. The server will provide data source
specifications (i.e., a remote Catalog), and may also provide the raw data, in
situations where the client is not able or not allowed to access it directly. As
such, the server can act as a gatekeeper of the data for security and monitoring
purposes. The implementation of the server in Intake is accessible as the
intake-server command, and acts as a reference: other implementations can easily be
created for specific circumstances.
TTL Time-to-live, how long before the given entity is considered to have expired.
Usually in seconds.
User Parameter
A data source definition can contain a "parameters" section, which can act as
explicit decision indicators for the user, or as validation and type coersion for
the definition's Argument s. See paramdefs.
YAML A text-based format for expressing data with a dictionary (key-value) and list
structure, with a limited number of data-types, such as strings and numbers. YAML
uses indentations to nest objects, making it easy to read and write for humans,
compared to JSON. Intake's catalogs and config are usually expressed in YAML files.
COMMUNITY
Intake is used and developed by individuals at a variety of institutions. It is open
source (license) and sits within the broader Python numeric ecosystem commonly referred to
as PyData or SciPy.
Discussion
Conversation happens in the following places:
1. Usage questions are directed to Stack Overflow with the #intake tag. Intake developers
monitor this tag.
2. Bug reports and feature requests are managed on the GitHub issue tracker. Individual
intake plugins are managed in separate repositories each with its own issue tracker.
Please consult the plugin-directory for a list of available plugins.
3. Chat occurs on at gitter.im/ContinuumIO/intake. Note that because gitter chat is not
searchable by future users we discourage usage questions and bug reports on gitter and
instead ask people to use Stack Overflow or GitHub.
4. Monthly community meeting happens the first Thursday of the month at 9:00 US Central
Time. See https://github.com/intake/intake/issues/596, with a reminder sent out on the
gitter channel. Strictly informal chatter.
Asking for help
We welcome usage questions and bug reports from all users, even those who are new to using
the project. There are a few things you can do to improve the likelihood of quickly
getting a good answer.
1. Ask questions in the right place: We strongly prefer the use of Stack Overflow or
GitHub issues over Gitter chat. GitHub and Stack Overflow are more easily searchable
by future users, and therefore is more efficient for everyone's time. Gitter chat is
strictly reserved for developer and community discussion.
If you have a general question about how something should work or want best practices
then use Stack Overflow. If you think you have found a bug then use GitHub
2. Ask only in one place: Please restrict yourself to posting your question in only one
place (likely Stack Overflow or GitHub) and don't post in both
3. Create a minimal example: It is ideal to create minimal, complete, verifiable
examples. This significantly reduces the time that answerers spend understanding your
situation, resulting in higher quality answers more quickly.
• genindex
• modindex
• search
AUTHOR
Anaconda
COPYRIGHT
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