Note: This document is for an older version of GRASS GIS that will be discontinued soon. You should upgrade, and read the current manual page.
NAME
r.statistics - Calculates category or object oriented statistics.
KEYWORDS
raster,
statistics,
zonal statistics
SYNOPSIS
r.statistics
r.statistics --help
r.statistics [-c] base=name cover=name method=string output=name [--overwrite] [--help] [--verbose] [--quiet] [--ui]
Flags:
- -c
- Cover values extracted from the category labels of the cover map
- --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:
- base=name [required]
- Name of base raster map
- cover=name [required]
- Name of cover raster map
- method=string [required]
- Method of object-based statistic
- Options: diversity, average, mode, median, avedev, stddev, variance, skewness, kurtosis, min, max, sum
- diversity: Diversity of values in specified objects in %%
- average: Average of values in specified objects
- mode: Mode of values in specified objects
- median: Median of values in specified objects
- avedev: Average deviation of values in specified objects
- stddev: Standard deviation of values in specified objects
- variance: Variance of values in specified objects
- skewness: Skewnes of values in specified objects
- kurtosis: Kurtosis of values in specified objects
- min: Minimum of values in specified objects
- max: Maximum of values in specified objects
- sum: Sum of values in specified objects
- output=name [required]
- Resultant raster map
r.statistics is a tool to analyse exploratory statistics of a categorical
"cover layer" according to how it intersects with objects in a "base layer". A
variety of standard statistical measures are possible (called "zonal statistics"
in some GIS).
All cells in the base layer are considered one object for the analysis. For
some applications, one will first want to prepare the input data so that
all areas of contiguous cell category values in the base layer are uniquely
identified, which can be done with
r.clump.
The available methods are the following:
- average deviation
- average
- diversity
- kurtosis
- maximum
- median
- minimum
- mode
- skewness
- standard deviation
- sum
- variance
The calculations will be performed on each area of data of the
cover layers which fall within each unique value, or category, of the base layer.
Setting the -c flag the category labels of the covering raster
layer will be used. This is nice to avoid the GRASS limitation to integer
in raster maps because using category values floating point numbers can be
stored.
All calculations create an output layer. The output
layer is a reclassified version of the base layer with identical
category values, but modified category labels - the results of the calculations
are stored in the category labels of the output layer.
For floating-point cover map support, see the alternative
r.stats.zonal.
For quantile calculations with support for floating-point cover maps, see the
alternative
r.stats.quantile.
Calculation of average elevation of each field in the Spearfish region:
r.statistics base=fields cover=elevation.dem out=elevstats method=average
r.category elevstats
r.mapcalc "fieldelev = @elevstats"
r.univar fieldelev
r.category,
r.clump,
r.mode,
r.mapcalc,
r.neighbors,
r.stats.quantile,
r.stats.zonal,
r.univar
Martin Schroeder, Geographisches Institut Heidelberg, Germany
SOURCE CODE
Available at:
r.statistics source code
(history)
Latest change: Monday Jan 30 09:36:46 2023 in commit: 0fb05e493f4ef73f4a721b019bffc357be2ec8d6
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GRASS Development Team,
GRASS GIS 8.3.3dev Reference Manual