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

6       r.what   -  Queries  raster  maps on their category values and category
7       labels.
8

KEYWORDS

10       raster, querying, position
11

SYNOPSIS

13       r.what
14       r.what --help
15       r.what    [-nfricv]    map=name[,name,...]     [coordinates=east,north]
16       [points=name]    [null_value=string]   [output=name]   [separator=char‐
17       acter]     [cache=integer]     [--overwrite]    [--help]    [--verbose]
18       [--quiet]  [--ui]
19
20   Flags:
21       -n
22           Output header row
23
24       -f
25           Show the category labels of the grid cell(s)
26
27       -r
28           Output color values as RRR:GGG:BBB
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30       -i
31           Output integer category values, not cell values
32
33       -c
34           Turn on cache reporting
35
36       -v
37           Show the category for vector points map
38
39       --overwrite
40           Allow output files to overwrite existing files
41
42       --help
43           Print usage summary
44
45       --verbose
46           Verbose module output
47
48       --quiet
49           Quiet module output
50
51       --ui
52           Force launching GUI dialog
53
54   Parameters:
55       map=name[,name,...] [required]
56           Name of existing raster map(s) to query
57
58       coordinates=east,north
59           Coordinates for query
60
61       points=name
62           Name of vector points map for query
63           Or data source for direct OGR access
64
65       null_value=string
66           String representing NULL value
67           Default: *
68
69       output=name
70           Name for output file (if omitted or "-" output to stdout)
71
72       separator=character
73           Field separator
74           Special characters: pipe, comma, space, tab, newline
75           Default: pipe
76
77       cache=integer
78           Size of point cache
79           Default: 500
80

DESCRIPTION

82       r.what outputs the category values and (optionally) the category labels
83       associated with user-specified locations on raster input map(s).  Loca‐
84       tions  are  specified as geographic x,y coordinate pairs (i.e., pair of
85       eastings and northings); the user can  also  (optionally)  associate  a
86       label with each location.
87
88       The  input  coordinates can be entered directly on the command line via
89       coordinates parameter, or redirected via stdin from an input text file,
90       script,  or  piped from another program (like v.out.ascii). Coordinates
91       can be given also as a vector points map (points).
92
93       If none of the above input methods are used and the module is run  from
94       the  terminal prompt, the program will interactively query the user for
95       point locations and labels.
96
97       Each line of the input consists of  an  easting,  a  northing,  and  an
98       optional label, which are separated by spaces. In interactive mode, the
99       word "end" must be typed after the last pair of input coordinates.
100
101       r.what output consists of the input geographic location and label, and,
102       for  each  user-named raster map layer, the category value, and (if the
103       -f label flag is specified) the  category  label  associated  with  the
104       cell(s) at this geographic location.
105

EXAMPLES

107   Input coordinates given as an option
108       The  module’s  coordinates  parameter  can  be used to enter coordinate
109       pairs directly. The maximum number of pairs will  be  limited  by  your
110       system’s maximum input line length (e.g. 4096 characters).
111       g.region raster=landuse96_28m,aspect -p
112       r.what map=landuse96_28m,aspect coordinates=633614.08,224125.12,632972.36,225382.87 -f
113       633614.08|224125.12||2|Low Intensity Developed|209.5939|209 degrees ccw from east
114       632972.36|225382.87||15|Southern Yellow Pine|140.7571|140 degrees ccw from east
115
116   Input coordinates given as a vector points map
117       Coordinates  can  be read from existing vector points map by specifying
118       points option. Other features than points  or  centroids  are  ignored.
119       Example: query North Carolina county number for each community college:
120       g.region raster=boundary_county_500m -p
121       r.what map=boundary_county_500m points=comm_colleges
122       145096.859150|154534.264884||39
123       616341.437150|146049.750884||51
124       ...
125
126   Input coordinates given as a vector points map with cats
127       Coordinates  can  be read from existing vector points map by specifying
128       points option. Other features than points  or  centroids  are  ignored.
129       Using  the  v  flag you can get also the cat for each feature. Example:
130       query North Carolina county number for each community college:
131       g.region raster=boundary_county_500m -p
132       r.what map=boundary_county_500m points=comm_colleges -v
133       1|145096.859150|154534.264884||39
134       2|616341.437150|146049.750884||51
135       ...
136
137   Input coordinates given as a vector points map, output into CSV file
138       Coordinates can be read from existing vector points map  by  specifying
139       points option. Other features than points or centroids are ignored. The
140       output is stored in a CSV file including  header  row.  Example:  query
141       North Carolina county number for each community college:
142       g.region raster=boundary_county_500m -p
143       r.what map=boundary_county_500m points=comm_colleges \
144              separator=comma output=result.csv -n
145       cat result.csv
146       easting,northing,site_name,boundary_county_500m
147       145096.859150,154534.264884,,39
148       616341.437150,146049.750884,,51
149       410595.719150,174301.828884,,71
150       ...
151
152   Input from a text file containing coordinates
153       The  contents of an ASCII text file can be redirected to r.what as fol‐
154       lows. If we have a file called input_coord.txt  containing  the  white‐
155       space separated coordinates and optionally labels, the resulting raster
156       map values are extracted:
157       cat input_coord.txt
158       633614.08 224125.12 site 1
159       632972.36 225382.87 site 2
160       r.what map=landuse96_28m,aspect < input_coord.txt
161       633614.08|224125.12|site 1|2|209.5939
162       632972.36|225382.87|site 2|15|140.7571
163
164   Input from standard input on the command line
165       Input coordinates may be given directly from  standard  input  (stdin),
166       for example (input data appears between the "EOF" markers):
167       r.what map=landuse96_28m,aspect << EOF
168       633614.08 224125.12 site 1
169       632972.36 225382.87 site 2
170       EOF
171       633614.08|224125.12|site 1|2|209.5939
172       632972.36|225382.87|site 2|15|140.7571
173       echo "633614.08 224125.12" | r.what map=landuse96_28m,aspect
174       633614.08|224125.12||2|209.5939
175
176   Input coordinates piped from another program
177       The  input coordinates may be "piped" from the standard output (stdout)
178       of another program. In the next example, vector point  coordinates  are
179       piped from the v.out.ascii module.
180       v.out.ascii comm_colleges separator=space | r.what map=boundary_county_500m
181       145096.8591495|154534.26488388|1|39
182       616341.4371495|146049.75088388|2|51
183       410595.7191495|174301.82888388|3|71
184       ...
185
186   Output containing raster map category labels
187       Here  we  use the -f label flag to enable the output of category labels
188       associated with the raster cell(s), as well as values (categorical maps
189       only).
190       r.what -f map=landuse96_28m,aspect << EOF
191       633614.08 224125.12 site 1
192       632972.36 225382.87 site 2
193       EOF
194       633614.08|224125.12|site 1|2|Low Intensity Developed|209.5939|209 degrees ccw from east
195       632972.36|225382.87|site 2|15|Southern Yellow Pine|140.7571|140 degrees ccw from east
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NOTE

198       The maximum number of raster map layers that can be queried at one time
199       is 400.
200

TODO

202           ·   Fix 400 maps limit
203

SEE ALSO

205          r.category,   r.report,   r.stats,   r.series,   r.univar,   v.what,
206       v.what.rast, v.what.vect
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AUTHOR

209       Michael Shapiro, U.S. Army Construction Engineering Research Laboratory
210       Vector point input added by Martin Landa, Czech Technical University in
211       Prague, Czech Republic
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213       Last changed: $Date: 2017-05-16 16:04:44 +0200 (Tue, 16 May 2017) $
214

SOURCE CODE

216       Available at: r.what source code (history)
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218       Main index | Raster index | Topics index | Keywords index  |  Graphical
219       index | Full index
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221       © 2003-2019 GRASS Development Team, GRASS GIS 7.6.0 Reference Manual
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225GRASS 7.6.0                                                          r.what(1)
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