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v.rast.stats(1)		    GRASS GIS User's Manual	       v.rast.stats(1)

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]     [where=sql_query]
       raster=name[,name,...]		     column_prefix=string[,string,...]
       [method=string[,string,...]]   [percentile=integer]   [--help]  [--ver-
       bose]  [--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=nameA [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 ac-
	   cess	this is	the layer name.
	   Default: 1

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

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

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

       method=string[,string,...]
	   The methods to use
	   Options: number, null_cells,	minimum, maximum, range, average, std-
	   dev,	variance, coeff_var, sum, first_quartile, median,  third_quar-
	   tile, percentile
	   Default:	  number,null_cells,minimum,maximum,range,average,std-
	   dev,variance,coeff_var,sum,first_quartile,median,third_quar-
	   tile,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 uni-
       variate 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 re-
       quested 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  val-
       ues, range, average, standard deviation,	variance, coefficient of vari-
       ation, 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 ad-
       ditional	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	calcu-
       lated using any size input region.

EXAMPLES
       Example	to  upload  DEM	statistics to ZIP codes	vector map (North Car-
       olina 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)

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

       A(C) 2003-2020 GRASS Development	Team, GRASS GIS	7.8.3 Reference	Manual

GRASS 7.8.3						       v.rast.stats(1)

NAME | KEYWORDS | SYNOPSIS | DESCRIPTION | NOTES | EXAMPLES | SEE ALSO | AUTHOR | SOURCE CODE

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