r.statistics.1grass man page

r.statistics — Calculates category or object oriented statistics.


raster, statistics, zonal statistics


r.statistics --help
r.statistics [-c] base=name cover=name method=string output=name [--overwrite] [--help] [--verbose] [--quiet] [--ui]


Cover values extracted from the category labels of the cover map
Allow output files to overwrite existing files
Print usage summary
Verbose module output
Quiet module output
Force launching GUI dialog


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 "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 (english - german):

average - Durchschnitt
mode - Modalwert
median - Median
average deviation - Durchschnittliche Abweichung
standard deviation - Standardabweichung
variance - Varianz
skewness - Schiefe der Verteilung
kurtosis - Relative Abflachung (-) oder Zuspitzung (+)
minimum - Minimum
maximum - Maximum
sum - Summe

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 lables 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.


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

See Also

r.category, r.clump, r.mode, r.mapcalc, r.neighbors, r.stats.quantile, r.stats.zonal, r.univar


Martin Schroeder, Geographisches Institut Heidelberg, Germany

Last changed: $Date: 2015-12-31 09:19:51 +0100 (Thu, 31 Dec 2015) $

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