NAME

       r.median   - Finds the median of values in a cover map within areas assigned the same category value in a
       user-specified base map.

KEYWORDS

       raster, statistics

SYNOPSIS

       r.median
       r.median help
       r.median base=name cover=name output=name  [--overwrite]  [--verbose]  [--quiet]

   Flags:
       --overwrite
           Allow output files to overwrite existing files

       --verbose
           Verbose module output

       --quiet
           Quiet module output

   Parameters:
       base=name
           Name of base raster map

       cover=name
           Name of cover raster map

       output=name
           Name for output raster map

DESCRIPTION

       r.median calculates the median category of data contained in a cover raster map layer for areas  assigned
       the  same  category value in the user-specified base raster map layer.  These median values are stored in
       the new output map layer.

       The output map is actually a reclass of the base map.  The base  map is an existing raster map  layer  in
       the  user's  current mapset search path.  For each group of cells assigned the same category value in the
       base map, the median of the values assigned these cells in the cover map will be computed.

       The cover map is an existing raster map layer containing the values to be  used  to  compute  the  median
       within each category of the base map.

NOTES

       The  user  should use the results of r.median with care.  Since this utility assigns a value to each cell
       which is based on global information (i.e., information at spatial locations other than just the location
       of the cell itself), the resultant map layer is only valid if the geographic region and mask settings are
       the same as they were at the time that the result map was created.

       Results are affected by the current region settings and mask.

EXAMPLE

       Median K-factor (erosion) for Spearfish fields:
       g.region rast=fields -p
       r.median base=fields cover=soils.Kfactor output=K.by.farm.median
       r.univar K.by.farm.median

SEE ALSO

       g.region,  r.average,  r.category,  r.clump,  r.describe,  r.mapcalc,  r.mfilter,  r.mode,   r.neighbors,
       r.reclass, r.statistics, r.stats, r.univar

AUTHOR

       Michael Shapiro, U.S.Army Construction Engineering Research Laboratory

       Last changed: $Date: 2008-05-16 12:09:06 -0700 (Fri, 16 May 2008) $

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       © 2003-2013 GRASS Development Team