d.what.rast - Allows the user to interactively query the category
contents of multiple raster map layers at user-specified locations within
the current geographic region.
(GRASS Display Program)
d.what.rast [-1tc] [map=name[,name,...]]
d.what.rast outputs the category values and labels
associated with cell(s) at user-specified location(s) on
user-named raster map layer(s).
The program will query the contents of raster map layer(s)
named by the user on the command line. These map layers
must exist in the user's current mapset search path. If
the user does not name any raster map layers on the command
line, d.what.rast will query the category contents
of whatever raster map layer is already displayed in the
active frame on the graphics monitor.
The program activates the mouse, and expects the user to
indicate the cell location(s) to be queried by depressing a
mouse button over desired location(s) within the current
geographic region in the active display frame on the
- Identify and query just one point location. Only one mouse click is
executed. This option is provided for shell scripts and programs that
want to obtain only one point from the user.
- Provide only terse output. This option is provided to simplify the
parsing of output by other programs.
- Print out column and row for entire map region.
- Name of existing raster map layer(s). Limit: 15 maps
Default: Query map currently displayed in the active graphics frame.
- Output field separator to be used (in terse mode only).
d.what.rast output consists of the geographic
coordinates of the location pointed to, and, for each map
layer, the map layer name, the category value, and category
label in the named raster map layers at this location.
It is helpful, but not necessary, to first display a map to
be used for reference in the active display frame before
running d.what.rast. For example, the user might
type the following series of commands and receive the
To first display the soils map in the active frame.
User then moves the mouse to desired location on the
displayed soils map layer, and presses the left
mouse button to query the category contents of the
soils and aspect maps at this geographic
location. The program then outputs the below information
to the user's terminal.
soils in PERMANENT (44)Nunn clay loam, NdC
aspect in PERMANENT (20)15 degrees north of west
The first line of output gives the easting (E) and northing (N) coordinates
of the geographic location at which the user clicked the mouse.
The subsequent two lines give the map name and mapset, map category value
(within parentheses), and map category label corresponding to this
user-selected map location, for each of the maps queried by the user.
The query may be repeated as often as desired using the
left mouse button. The right button on the mouse is used
to quit the d.what.rast session.
Users can set the -t flag to obtain a terse output
from d.what.rast. This is useful when the user
wishes output to be parsed by another program (like
awk). If the -t flag is set, users can also
select the field separator used (with the
fs=name option), or elect to use the
default : field separator. In this case, the
produces output in the form shown below. The first line of
output gives the easting, northing, and the mouse button
return value (see NOTES, below). Each
subsequent line gives the map name and its mapset, the
category value, and category label of the point specified
on the user-named raster map layers. The default output
field separator, a colon, is used since none was specified
on the command line.
- d.what.rast -t map=soils,aspect
soils@PERMANENT:44:Nunn clay loam, NdC
aspect@PERMANENT:20:15 degrees north of west
Users can also use this program inside of shell scripts
that require as input a map category value and a mouse
button depressed. Users can choose an option to run
d.what.rast only once, and return only the map
category value found and the number of the mouse button
Mouse button return values are as follows: 0 indicates no
button was pressed, 1 indicates that the left mouse button
was pressed, 2 indicates the middle button was pressed, and
3 indicates that the right mouse button was pressed.
d.what.rast will always print its output to the
terminal screen. d.what.rast output can be
redirected into a file; however, if it is, the output will
go both to the screen and to the file. For example:
will both send d.what.rast output to the screen
and capture its output in the file named
d.what.rast map=soils,aspect > what.out
The maximum number of raster map layers that can be queried
at one time is 15.
allows the user to interactively query the category
contents of multiple vector map layers at user-specified
U.S. Army Construction Engineering