1r.what(1) Grass User's Manual r.what(1)
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6 r.what - Queries raster map layers on their category values and cate‐
7 gory labels.
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10 raster
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13 r.what
14 r.what help
15 r.what [-fci] input=string[,string,...] [cache=integer]
16 [null=string] [east_north=east,north[,east,north,...]]
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18 Flags:
19 -f Show the category label in the grid cell(s)
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21 -c Turn on cache reporting
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23 -i Output integer category values, not cell values
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25 Parameters:
26 input=string[,string,...]
27 Name of existing raster map(s) to query
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29 cache=integer
30 Size of point cache Default: 500
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32 null=string
33 Char string to represent no data cell Default: *
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35 east_north=east,north[,east,north,...]
36 Coordinates for query
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39 r.what outputs the category values and (optionally) the category labels
40 associated with user-specified locations on raster input map(s). Loca‐
41 tions are specified as geographic x,y coordinate pairs (i.e., pair of
42 eastings and northings); the user can also (optionally) associate a
43 label with each location.
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45 The input coordinates can be entered directly on the command line, or
46 redirected via stdin from an input text file, script, or piped from
47 another program (like d.where).
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49 If none of the above input methods are used and the module is run from
50 the terminal prompt, the program will interactively query the user for
51 point locations and labels.
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53 Each line of the input consists of an easting, a northing, and an
54 optional label, which are separated by spaces. In interactive mode, the
55 word "end" must be typed after the last pair of input coordinates.
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57 r.what output consists of the input geographic location and label, and,
58 for each user-named raster map layer, the category value, and (if the
59 -f label flag is specified) the category label associated with the
60 cell(s) at this geographic location.
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63 Input from stdin on the command line
64 Input coordinates may be given directly from stdin, for example:
65 (input data appears between the "EOF" markers)
66 r.what input=soils,aspect << EOF
67 635342.21 7654321.09 site 1
68 653324.88 7563412.42 site 2
69 EOF
70 635342.21|7654321.09|site 1|45|21
71 653324.88|7563412.42|site 2|44|20
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73 echo "635342.21 7654321.09" | r.what input=soils,aspect
74 635342.21|7654321.09|45|21
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77 Input from a text file containing coordinates
78 The contents of an ASCII text file can be redirected to r.what as fol‐
79 lows. If we have a file called input_coord.txt containing the coordi‐
80 nates and labels given in the example above:
81 r.what input=soils,aspect < input_coord.txt
82 635342.21|7654321.09|site 1|45|21
83 653324.88|7563412.42|site 2|44|20
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86 Input coordinates given as a module option
87 The module's east_north parameter can be used to enter coordinate pairs
88 directly. The maximum number of pairs will be limited by your system's
89 maximum input line length (e.g. 4096 characters).
90 r.what input=soils,aspect
91 east_north=635342.21,7654321.09,653324.88,7563412.42
92 635342.21|7654321.09|45|21
93 653324.88|7563412.42|44|20
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96 Input coordinates piped from another program
97 The input coordinates may be "piped" from the stdout of another pro‐
98 gram. For example:
99 d.where | r.what input=soils,aspect
100 635342.21|7654321.09|45|21
101 653324.88|7563412.42|44|20
102 In the next example, vector point coordinates are piped from the
103 v.out.ascii module . The standard UNIX program "tr" is used to convert
104 the column separators in v.out.ascii's output into spaces for r.what.
105 v.out.ascii bugsites fs=' ' | r.what input=soils,aspect
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108 Output containing raster map category labels
109 Here we use the -f label flag to enable the output of category labels
110 associated with the raster cell(s), as well as values. (categorical
111 maps only)
112 r.what -f input=soils,aspect << EOF
113 635342.21 7654321.09 site 1
114 653324.88 7563412.42 site 2
115 EOF
116 635342.21|7654321.09|site 1|45|NaC|21|30 degrees NW
117 653324.88|7563412.42|site 2|44|NdC|20|15 degrees NW
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121 The maximum number of raster map layers that can be queried at one time
122 is 150.
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125 d.where, r.cats, r.report, r.stats, r.series, r.univar, v.what,
126 v.what.rast, v.what.vect
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129 Michael Shapiro, U.S. Army Construction Engineering Research Laboratory
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131 Last changed: $Date: 2007/03/23 22:54:16 $
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133 Full index
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137GRASS 6.2.2 r.what(1)