## table of contents

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

# 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**] [--**verbose**]
[--**quiet**] [--**ui**]

## Flags:¶

## 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* **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.

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)

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© 2003-2020 GRASS Development Team, GRASS GIS 7.8.5 Reference Manual

GRASS 7.8.5 |