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

DESCRIPTION

       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.

EXAMPLES

       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

AUTHOR

       Martin Schroeder, Geographisches Institut Heidelberg, Germany

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

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       © 2003-2016 GRASS Development Team, GRASS GIS 7.0.3 Reference Manual