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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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