1r.median(1) Grass User's Manual r.median(1)
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6 r.median - Finds the median of values in a cover map within areas
7 assigned the same category value in a user-specified base map.
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10 raster
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13 r.median
14 r.median help
15 r.median base=name cover=name output=name [--overwrite] [--verbose]
16 [--quiet]
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18 Flags:
19 --overwrite
20 Allow output files to overwrite existing files
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22 --verbose
23 Verbose module output
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25 --quiet
26 Quiet module output
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28 Parameters:
29 base=name
30 Name of base raster map
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32 cover=name
33 Name of cover raster map
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35 output=name
36 Name for output raster map
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39 r.median calculates the median category of data contained in a cover
40 raster map layer for areas assigned the same category value in the
41 user-specified base raster map layer. These median values are stored
42 in the new output map layer.
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44 The output map is actually a reclass of the base map. The base map is
45 an existing raster map layer in the user's current mapset search path.
46 For each group of cells assigned the same category value in the base
47 map, the median of the values assigned these cells in the cover map
48 will be computed.
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50 The cover map is an existing raster map layer containing the values to
51 be used to compute the median within each category of the base map.
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54 The user should use the results of r.median with care. Since this
55 utility assigns a value to each cell which is based on global informa‐
56 tion (i.e., information at spatial locations other than just the loca‐
57 tion of the cell itself), the resultant map layer is only valid if the
58 geographic region and mask settings are the same as they were at the
59 time that the result map was created.
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61 Results are affected by the current region settings and mask.
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64 Median K-factor (erosion) for Spearfish fields:
65 g.region rast=fields -p
66 r.median base=fields cover=soils.Kfactor output=K.by.farm.median
67 r.univar K.by.farm.median
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71 g.region, r.average, r.category, r.clump, r.describe, r.mapcalc,
72 r.mfilter, r.mode, r.neighbors, r.reclass, r.statistics, r.stats,
73 r.univar
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76 Michael Shapiro, U.S.Army Construction Engineering Research Laboratory
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78 Last changed: $Date: 2007-10-10 10:01:00 +0200 (Wed, 10 Oct 2007) $
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80 Full index
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82 © 2003-2008 GRASS Development Team
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86GRASS 6.3.0 r.median(1)