Provided by: grass-doc_7.4.0-1_all

**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.statsv.rast.stats--helpv.rast.stats[-cd]map=name[layer=string]raster=namecolumn_prefix=string[method=string[,string,...]] [percentile=integer] [--help] [--verbose] [--quiet] [--ui]Flags:-cContinue if upload column(s) already exist-dCreate densified lines (default: thin lines) All cells touched by the line will be set, not only those on the render path--helpPrint usage summary--verboseVerbose module output--quietQuiet module output--uiForce launching GUI dialogParameters:map=name[required]Name of vector map Or data source for direct OGR accesslayer=stringLayer 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:1raster=name[required]Name of input raster map to calculate statistics fromcolumn_prefix=string[required]Column prefix for new attribute columnsmethod=string[,string,...] The methods to use Options:number,minimum,maximum,range,average,stddev,variance,coeff_var,sum,first_quartile,median,third_quartile,percentileDefault:number,minimum,maximum,range,average,stddev,variance,coeff_var,sum,first_quartile,median,third_quartile,percentilepercentile=integerPercentile to calculate Options:0-100Default:90

**DESCRIPTION**

v.rast.statscalculates 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 inmethod(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.statsis 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--verboseflag 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-ccontinue 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)Lastchanged:$Date:2017-02-1512:56:19+0100(Wed,15Feb2017)$

**SOURCE** **CODE**

Available at: v.rast.stats source code (history) Main index | Vector index | Topics index | Keywords index | Graphical index | Full index © 2003-2018 GRASS Development Team, GRASS GIS 7.4.0 Reference Manual