Provided by: grass-doc_8.3.0-1_all bug

NAME

       v.rast.stats   -  Calculates univariate statistics from a raster map based on a vector map
       and uploads statistics to new attribute columns.

KEYWORDS

       vector, statistics, raster, univariate statistics, zonal statistics, sampling, querying

SYNOPSIS

       v.rast.stats
       v.rast.stats --help
       v.rast.stats     [-cd]     map=name       [layer=string]        [type=string[,string,...]]
       [where=sql_query]          raster=name[,name,...]        column_prefix=string[,string,...]
       [method=string[,string,...]]    [percentile=integer]    [--help]   [--verbose]   [--quiet]
       [--ui]

   Flags:
       -c
           Continue if upload column(s) already exist

       -d
           Create densified lines (default: thin lines)
           All cells touched by the line will be set, not only those on the render path

       --help
           Print usage summary

       --verbose
           Verbose module output

       --quiet
           Quiet module output

       --ui
           Force launching GUI dialog

   Parameters:
       map=name [required]
           Name of vector map
           Or data source for direct OGR access

       layer=string
           Layer number or name
           Vector  features  can have category values in different layers. This number determines
           which layer to use. When used with direct OGR access this is the layer name.
           Default: 1

       type=string[,string,...]
           Input feature type
           Options: point, line, boundary, centroid, area
           Default: point,line,boundary,centroid,area

       where=sql_query
           WHERE conditions of SQL statement without ’where’ keyword
           Example: income < 1000 and population >= 10000

       raster=name[,name,...] [required]
           Name of input raster map to calculate statistics from

       column_prefix=string[,string,...] [required]
           Column prefix for new attribute columns

       method=string[,string,...]
           The methods to use
           Options: number, null_cells,  minimum,  maximum,  range,  average,  stddev,  variance,
           coeff_var, sum, first_quartile, median, third_quartile, percentile
           Default:
           number,null_cells,minimum,maximum,range,average,stddev,variance,coeff_var,sum,first_quartile,median,third_quartile,percentile

       percentile=integer
           Percentile to calculate
           Options: 0-100
           Default: 90

DESCRIPTION

       v.rast.stats  calculates  basic univariate statistics from a raster map only for the parts
       covered by the specified vector map.  The vector map will be rasterized according  to  the
       raster  map  resolution.   Then  univariate  statistics are calculated per vector category
       (cat) from the raster map and the results uploaded to the vector map attribute  table.   A
       new  column is generated in the attribute table for each statistic requested in method (if
       not already present).

       The univariate statistics include the number of raster cells counted, the number of raster
       NULL  cells  counted, minimum and maximum cell values, range, average, standard deviation,
       variance, coefficient of variation, sum,  first  quartile,  median,  third  quartile,  and
       percentile.

NOTES

       v.rast.stats is only meaningful for lines or polygons.

       The  module  may  take  a long time to run if the raster region contains a large number of
       cells. In this case the --verbose flag may be used to track progress.

       The script stops if a (prefixed) upload column  is  already  present  in  the  vector  map
       attribute  table, unless otherwise instructed with the -c continue flag. The column prefix
       will be separated from the statistic name with an underscore. For example with a prefix of
       "elev" the sum column will be named elev_sum.

       If  a  DBF  database  is  being  used,  note  that  column names are restricted by the DBF
       specification to 10 characters. Therefore it is advised to be economical in the use of the
       column prefix when using DBF as any additional characters will be chopped off.

       If  a  MASK is present, it will be restored after the script finished.  The script changes
       temporarily to the resolution of the given raster map.

       If an area has several  categories  in  the  selected  layer  (equivalent  to  overlapping
       polygons  in  Simple  Features),  only  one category will be kept during the rasterization
       process. Statistics for the skipped categories will thus be partial.

       For example, if there are three areas: area 1 with cat 1, area 2 with cat 2, area  3  with
       cats  1,  2.  Only  one category value of area 3 will be used for rasterization, the other
       category value will be skipped. Thus statistics  for  the  used  category  value  will  be
       complete, while statistics for the skipped category value will be incomplete.

       Large    amounts    of    system   memory   can   be   used   when   extended   statistics
       (first_quartile,median,third_quartile,percentile ) are being requested with a  very  large
       region  setting.  If  the  region is too large the module should display memory allocation
       errors. Basic statistics can be calculated using any size input region.

EXAMPLES

       Example to upload DEM statistics to ZIP codes vector map (North Carolina sample dataset):
       g.copy vect=zipcodes_wake,myzipcodes_wake
       # set computational region to DEM:
       g.region raster=elevation -p
       # calculate selected DEM statistics, upload to vector map table:
       v.rast.stats myzipcodes_wake raster=elevation \
         column_prefix=elev method=minimum,maximum,average,range,stddev,percentile \
         percentile=95
       # verify results:
       v.info -c myzipcodes_wake
       v.db.select myzipcodes_wake
       v.univar myzipcodes_wake column=elev_range type=centroid

SEE ALSO

        r.univar, v.univar, v.vect.stats, v.what.rast, v.what.rast3, v.what.vect

AUTHOR

       Markus Neteler, CEA (for the EDEN EU/FP6 Project)

SOURCE CODE

       Available at: v.rast.stats source code (history)

       Accessed: Tuesday Jun 27 11:14:35 2023

       Main index | Vector index | Topics index | Keywords index | Graphical index | Full index

       © 2003-2023 GRASS Development Team, GRASS GIS 8.3.0 Reference Manual