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NAME

       t.sample   -  Samples the input space time dataset(s) with a sample space time dataset and
       print the result to stdout.

KEYWORDS

       temporal, sampling, time

SYNOPSIS

       t.sample
       t.sample --help
       t.sample  [-cs]   inputs=name[,name,...]   sample=name    [intype=name]     [samtype=name]
       [method=name[,name,...]]     [separator=character]     [--help]    [--verbose]   [--quiet]
       [--ui]

   Flags:
       -c
           Print the column names as first row

       -s
           Check for spatial topological overlap

       --help
           Print usage summary

       --verbose
           Verbose module output

       --quiet
           Quiet module output

       --ui
           Force launching GUI dialog

   Parameters:
       inputs=name[,name,...] [required]
           Name of the input space time datasets

       sample=name [required]
           Name of the sample space time dataset

       intype=name
           Type of the input space time dataset
           Options: strds, stvds, str3ds
           Default: strds

       samtype=name
           Type of the sample space time dataset
           Options: strds, stvds, str3ds
           Default: strds

       method=name[,name,...]
           The method to be used for sampling the input dataset
           Options: start, during, overlap, contain, equal, follows, precedes
           Default: during,overlap,contain,equal

       separator=character
           Do not use "," as this char is reserved to list several map ids in a sample granule
           Field separator between output columns, default is tabular " | "
           Default: pipe

DESCRIPTION

       The purpose of this module is to compute and to  show  spatio-temporal  relations  between
       space  time datasets of different type. Several input space time datasets are sampled by a
       sample space time dataset using temporal topological relations. The  types  of  the  input
       space time datasets and the type of the sample space time dataset can be different.

       This  module is useful to analyze temporal relationships between space time datasets using
       temporal  topology.  The  flag  -s  enables  a  spatio-temporal  topology,  so  that  only
       spatio-temporal related map layers of space time datasets are considered in the analysis.

NOTES

       The  temporal relation start means that the start time of an input map layer is temporally
       located in an interval of a sample map layer.

       The textual output at the command line shows the names of the maps, start and end time  as
       well as the interval length in days and the temporal distance from begin in days.

       The default separator is the pipe symbol.

       Temporal  gaps,  if present, in the input and sampling space time datasets will be used in
       the sampling process. Gaps have no map name, instead None is printed.

EXAMPLE

       In the examples below we create a space time raster dataset A  and  a  space  time  vector
       dataset  P  that  have different temporal layouts and number of map layers. The space time
       vector dataset contains a gap, that will be used in the sampling process.

       We use t.sample to inspect the topological relations between the time stamped  map  layers
       in A and P.

       # Set an appropriate region
       g.region s=0 n=80 w=0 e=120 b=0 t=50 res=10 res3=10 -p3
       # Generate the raster map layer
       r.mapcalc expression="a1 = rand(0, 550)" -s
       r.mapcalc expression="a2 = rand(0, 450)" -s
       r.mapcalc expression="a3 = rand(0, 320)" -s
       r.mapcalc expression="a4 = rand(0, 510)" -s
       r.mapcalc expression="a5 = rand(0, 300)" -s
       r.mapcalc expression="a6 = rand(0, 650)" -s
       # Generate the vector map layer
       v.random -z output=pnts1 n=20 zmin=0 zmax=100 column=height
       v.random -z output=pnts2 n=20 zmin=0 zmax=100 column=height
       n1=`g.tempfile pid=1 -d`
       n2=`g.tempfile pid=2 -d`
       cat > "${n1}" << EOF
       a1
       a2
       a3
       a4
       a5
       a6
       EOF
       cat > "${n2}" << EOF
       pnts1|2001-01-01|2001-03-01
       pnts2|2001-05-01|2001-07-01
       EOF
       # Register the maps in new space time datasets
       t.create type=strds temporaltype=absolute output=A \
           title="A test with raster input files" descr="A test with raster input files"
       t.create type=stvds temporaltype=absolute output=P \
           title="A test with vector input files" descr="A test with vector input files"
       t.register type=raster -i input=A file="${n1}" start="2001-01-01" increment="1 months"
       # Raster map layer in A
       t.rast.list A
       name|mapset|start_time|end_time
       a1|PERMANENT|2001-01-01 00:00:00|2001-02-01 00:00:00
       a2|PERMANENT|2001-02-01 00:00:00|2001-03-01 00:00:00
       a3|PERMANENT|2001-03-01 00:00:00|2001-04-01 00:00:00
       a4|PERMANENT|2001-04-01 00:00:00|2001-05-01 00:00:00
       a5|PERMANENT|2001-05-01 00:00:00|2001-06-01 00:00:00
       a6|PERMANENT|2001-06-01 00:00:00|2001-07-01 00:00:00
       t.register type=vector input=P file="${n2}"
       # Vector map layer in P
       t.vect.list P
       name|layer|mapset|start_time|end_time
       pnts1|None|PERMANENT|2001-01-01 00:00:00|2001-03-01 00:00:00
       pnts2|None|PERMANENT|2001-05-01 00:00:00|2001-07-01 00:00:00
       # Start time of maps in A located in maps in P
       t.sample method=start input=A samtype=stvds sample=P -c
       P@PERMANENT|A@PERMANENT|start_time|end_time|interval_length|distance_from_begin
       pnts1@PERMANENT|a1@PERMANENT,a2@PERMANENT|2001-01-01 00:00:00|2001-03-01 00:00:00|59.0|0.0
       None|a3@PERMANENT,a4@PERMANENT|2001-03-01 00:00:00|2001-05-01 00:00:00|61.0|59.0
       pnts2@PERMANENT|a5@PERMANENT,a6@PERMANENT|2001-05-01 00:00:00|2001-07-01 00:00:00|61.0|120.0
       # P contains A
       t.sample method=contain input=A samtype=stvds sample=P -c
       P@PERMANENT|A@PERMANENT|start_time|end_time|interval_length|distance_from_begin
       pnts1@PERMANENT|a1@PERMANENT,a2@PERMANENT|2001-01-01 00:00:00|2001-03-01 00:00:00|59.0|0.0
       None|a3@PERMANENT,a4@PERMANENT|2001-03-01 00:00:00|2001-05-01 00:00:00|61.0|59.0
       pnts2@PERMANENT|a5@PERMANENT,a6@PERMANENT|2001-05-01 00:00:00|2001-07-01 00:00:00|61.0|120.0
       # A during P
       t.sample method=during intype=stvds input=P samtype=strds sample=A -c
       A@PERMANENT|P@PERMANENT|start_time|end_time|interval_length|distance_from_begin
       a1@PERMANENT|pnts1@PERMANENT|2001-01-01 00:00:00|2001-02-01 00:00:00|31.0|0.0
       a2@PERMANENT|pnts1@PERMANENT|2001-02-01 00:00:00|2001-03-01 00:00:00|28.0|31.0
       a3@PERMANENT|None|2001-03-01 00:00:00|2001-04-01 00:00:00|31.0|59.0
       a4@PERMANENT|None|2001-04-01 00:00:00|2001-05-01 00:00:00|30.0|90.0
       a5@PERMANENT|pnts2@PERMANENT|2001-05-01 00:00:00|2001-06-01 00:00:00|31.0|120.0
       a6@PERMANENT|pnts2@PERMANENT|2001-06-01 00:00:00|2001-07-01 00:00:00|30.0|151.0
       # No Overlapping
       t.sample method=overlap input=A samtype=stvds sample=P -cs
       P@PERMANENT|A@PERMANENT|start_time|end_time|interval_length|distance_from_begin
       pnts1@PERMANENT|None|2001-01-01 00:00:00|2001-03-01 00:00:00|59.0|0.0
       None|None|2001-03-01 00:00:00|2001-05-01 00:00:00|61.0|59.0
       pnts2@PERMANENT|None|2001-05-01 00:00:00|2001-07-01 00:00:00|61.0|120.0
       t.sample method=precedes input=A samtype=stvds sample=P -c
       P@PERMANENT|A@PERMANENT|start_time|end_time|interval_length|distance_from_begin
       pnts1@PERMANENT|a3@PERMANENT|2001-01-01 00:00:00|2001-03-01 00:00:00|59.0|0.0
       None|a5@PERMANENT|2001-03-01 00:00:00|2001-05-01 00:00:00|61.0|59.0
       pnts2@PERMANENT|None|2001-05-01 00:00:00|2001-07-01 00:00:00|61.0|120.0
       t.sample method=follows  input=A samtype=stvds sample=P -c
       P@PERMANENT|A@PERMANENT|start_time|end_time|interval_length|distance_from_begin
       pnts1@PERMANENT|None|2001-01-01 00:00:00|2001-03-01 00:00:00|59.0|0.0
       None|a2@PERMANENT|2001-03-01 00:00:00|2001-05-01 00:00:00|61.0|59.0
       pnts2@PERMANENT|a4@PERMANENT|2001-05-01 00:00:00|2001-07-01 00:00:00|61.0|120.0
       t.sample method=precedes,follows input=A samtype=stvds sample=P -c
       P@PERMANENT|A@PERMANENT|start_time|end_time|interval_length|distance_from_begin
       pnts1@PERMANENT|a3@PERMANENT|2001-01-01 00:00:00|2001-03-01 00:00:00|59.0|0.0
       None|a5@PERMANENT,a2@PERMANENT|2001-03-01 00:00:00|2001-05-01 00:00:00|61.0|59.0
       pnts2@PERMANENT|a4@PERMANENT|2001-05-01 00:00:00|2001-07-01 00:00:00|61.0|120.0

SEE ALSO

        t.create, t.info

AUTHOR

       Sören Gebbert, Thünen Institute of Climate-Smart Agriculture

SOURCE CODE

       Available at: t.sample source code (history)

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