r3.univar.1grass man page

r3.univar — Calculates univariate statistics from the non-null cells of a 3D raster map.
Statistics include number of cells counted, minimum and maximum cell values, range, arithmetic mean, population variance, standard deviation, coefficient of variation, and sum.

Keywords

raster3d, statistics, univariate statistics

Synopsis

r3.univar
r3.univar --help
r3.univar [-get] map=name [zones=name] [output=name] [percentile=float[,float,...]] [separator=character] [--overwrite] [--help] [--verbose] [--quiet] [--ui]

Flags

-g
Print the stats in shell script style
-e
Calculate extended statistics
-t
Table output format instead of standard output format
--overwrite
Allow output files to overwrite existing files
--help
Print usage summary
--verbose
Verbose module output
--quiet
Quiet module output
--ui
Force launching GUI dialog

Parameters

map=name [required]
Name of 3D raster map
zones=name
3D Raster map used for zoning, must be of type CELL
output=name
Name for output file (if omitted or "-" output to stdout)
percentile=float[,float,...]
Percentile to calculate (requires extended statistics flag)
Options: 0-100
Default: 90
separator=character
Field separator
Special characters: pipe, comma, space, tab, newline
Default: pipe

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) $

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