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 21:09:06 +0200 (Fri, 16 May 2008) $
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