bionic (1) v.rast.stats.1grass.gz

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]        raster=name       column_prefix=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

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

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

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

       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 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)

       Last changed: $Date: 2017-02-15 12:56:19 +0100 (Wed, 15 Feb 2017) $

SOURCE CODE

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

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       © 2003-2018 GRASS Development Team, GRASS GIS 7.4.0 Reference Manual