## DESCRIPTION

r3.univar calculates the univariate statistics for a 3D raster map. This includes the number of cells counted, minimum and maximum cell values, range, arithmetic mean, population variance, standard deviation, coefficient of variation, and sum. Statistics are calculated separately for every category/zone found in the zones input map if given. If the -e extended statistics flag is given the 1st quartile, median, 3rd quartile, and given percentile are calculated. If the -g flag is given the results are presented in a format suitable for use in a shell script. If the -t flag is given the results are presented in tabular format with the given field separator. The table can immediately be converted to a vector attribute table which can then be linked to a vector, e.g. the vector that was rasterized to create the zones input raster.

## NOTES

As with most GRASS raster3d modules, r3.univar operates on the voxel array defined by the current 3d region settings, not the original extent and resolution of the input map. See g.region.

This module can use large amounts of system memory when the -e extended statistics flag is used with a very large region setting. If the region is too large the module should exit gracefully with a memory allocation error. Basic statistics can be calculated using any size input region.

## EXAMPLE

Computing univariate statistics of a 3D raster with randomly generated values:

    # generate random map
    r3.mapcalc "random_0_1 = rand(0., 1)" -s

    # compute univariate statistics
    r3.univar map=random_0_1

## TODO

mode, skewness, kurtosis

## SEE ALSO

g.region, r.univar, r.mode, r.quantile, r.series, r3.stats, r.statistics, v.rast.stats, v.univar

## AUTHORS

Soeren Gebbert
Code is based on r.univar from
Hamish Bowman, Otago University, New Zealand
and Martin Landa
Zonal loop by Markus Metz

Last changed: $Date: 2014-10-14 04:57:21 +0200 (Tue, 14 Oct 2014) $