r.statistics(1)

1r.statistics(1)               Grass User's Manual              r.statistics(1)
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NAME

6       r.statistics  - Category or object oriented statistics.
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KEYWORDS

9       raster
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SYNOPSIS

12       r.statistics
13       r.statistics help
14       r.statistics   [-c]   base=string   cover=string  method=string   [out‐
15       put=string]   [--overwrite]
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17   Flags:
18       -c  Cover values extracted from the category labels of the cover map
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20       --overwrite
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22   Parameters:
23       base=string
24           Base raster map
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26       cover=string
27           Cover raster map
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29       method=string
30           Method  of  object-based  statistic   Options:   distribution,aver‐
31           age,mode,median,avedev,stddev,variance,skewness,kurto‐
32           sis,min,max,sum
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34       output=string
35           Resultant raster map (not used with 'distribution')
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DESCRIPTION

38       r.statistics is a tool, where different class,  resp.  object  oriented
39       statistical analysis methods are possible.
40       The methods are the following (english - german):
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42                     distribution - Verteilung in Prozent
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44                     average - Durchschnitt
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46                     mode - Modalwert
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48                     median - Median
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50                     average deviation - Durchschnittliche Abweichung
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52                     standard deviation - Standardabweichung
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54                     variance - Varianz
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56                     skewness - Schiefe der Verteilung
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58                     kurtosis - Relative Abflachung (-) oder Zuspitzung (+)
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60                     minimum - Minimum
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62                     maximum - Maximum
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64                     sum - Summe
65       The calculations will be performed for areas with data of the covering-
66       layers which belong in the base-layer o the same category.
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68       Setting the -c flag the category lables of the  covering  raster  layer
69       will  be  used.  This is nice to avoid the GRASS limitation to interger
70       in raster maps because using category values floating point numbers can
71       be stored.
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73       The output-layer is a reclassified version of the base-layer with iden‐
74       tical category values.  The results of the calculations are  stored  in
75       the category labels of the output-layer.
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77       The  described  output  is valid for all calculations with exception of
78       distribution. Here the output is given to stdout. A file  name  eventu‐
79       ally  specified  will be ignored. The result will be a table with three
80       columns.  In the 1. column are the category values  of  the  base-layer
81       (a), in the 2.  column the associated value of the cover-Layers (b) and
82       in the 3. column the percentage of b from a. Example:
83       1   124  23
84       1   201  47
85       1   273  30
86       2   101  5
87       2   152  16
88       2   167  60
89       2   187  19
90            .
91            .
92            .
93        To transfer the values stored as category  labels  into  cell  values,
94       r.mapcalc can be used ('@' operator).
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EXAMPLE

97       Calculation of average elevation of each field in the Spearfish region:
98       r.statistics base=fields cover=elevation.dem out=elevstats method=aver‐
99       age
100       r.cats elevstats
101       r.mapcalc "fieldelev=@elevstats"
102       r.univar fieldelev
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REMARK

106       The source code of average, mode and median was taken from  some  GRASS
107       raster modules.
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BUGS

110       unkown
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AUTHOR

116       Martin Schroeder, Geographisches Institut Heidelberg, Germany
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118       Last changed: $Date: 2006/08/08 13:09:15 $
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120       Full index
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124GRASS 6.2.2                                                    r.statistics(1)