r.mapcalc.simple(1grass) GRASS GIS User's Manual r.mapcalc.simple(1grass)
NAME
r.mapcalc.simple - Calculates a new raster map from a simple r.mapcalc
expression.
KEYWORDS
raster, algebra, simple
SYNOPSIS
r.mapcalc.simple
r.mapcalc.simple --help
r.mapcalc.simple [-sqc] expression=string [a=name] [b=name]
[c=name] [d=name] [e=name] [f=name] output=name [seed=integer]
[--overwrite] [--help] [--verbose] [--quiet] [--ui]
Flags:
-s
Generate random seed (result is non-deterministic)
-q
Quote the map names
-c
Case sensitive variable names
--overwrite
Allow output files to overwrite existing files
--help
Print usage summary
--verbose
Verbose module output
--quiet
Quiet module output
--ui
Force launching GUI dialog
Parameters:
expression=string [required]
Formula (e.g. A-B or A*C+B)
a=name
Name of input A raster map
b=name
Name of input B raster map
c=name
Name of input C raster map
d=name
Name of input D raster map
e=name
Name of input E raster map
f=name
Name of input F raster map
output=name [required]
Name for output raster map
seed=integer
Seed for rand() function
DESCRIPTION
r.mapcalc.simple provides a wrapper to r.mapcalc. Up to 6 maps can be
combined using simple expressions.
The general syntax for the expression follows r.mapcalc expression for-
mat, for example, A + B or exp(A + B) are valid. The variables A, B,
..., F represent raster maps which are provided as options a, b, ...,
f.
The result name, i.e. the output raster map, is provided using the op-
tion output and, unlike r.mapcalc it is not part of the expression.
This module is meant for convenience (for users and programmers) while
the r.mapcalc module is a better choice for more complex expressions
and advanced usage.
NOTES
Differences to r.mapcalc module:
• The input raster map names and the output map raster name are
separate from the expression (formula) which uses generic vari-
able names (A, B, C, ...).
• The output raster name is not included in the expression.
• The expression is expected to be a single short one liner with-
out the function eval().
Differences to r.mapcalc.simple module in GRASS GIS 5 and 6:
• The primary purpose is not being a GUI front end to r.mapcalc,
but a wrapper which allows easy building of interfaces to
r.mapcalc (including GUIs).
• Whitespace (most notably spaces) are allowed (in the same way
as for r.mapcalc).
• The variable names are case-insensitive to allow the original
uppercase as well as lowercase as in option names (unless the
-c flag is used).
• Option names for each map are just one letter (not amap, etc.).
• Output option name is output as for other modules (not out-
file).
• Raster map names can be optionally quoted (the -q flag).
• There is no expert mode (which was just running r.mapcalc).
• The expression option is first, so it is possible to omit its
name in the command line (just like with r.mapcalc).
• Overwriting of outputs is done in the same way as with other
modules, so there is no flag to not overwrite outputs.
EXAMPLES
Basic examples
r.mapcalc.simple expression="0" output=zeros
r.mapcalc.simple expression="1" output=ones
r.mapcalc.simple expression="2" output=twos
r.mapcalc.simple expression="A + B + C" a=zeros b=ones c=twos output=result1
r.mapcalc.simple expression="(A * B) / 2 + 3 * C" a=zeros b=ones c=twos output=result2
Figure: r.mapcalc.simple graphical user interface
Example expressions
Addition:
A + B
No spaces around operators are not recommended for readability, but al-
lowed in the expression:
A+B
More complex expression with a function:
exp(A+C)+(B-2)*7
SEE ALSO
r.mapcalc, r3.mapcalc, t.rast.mapcalc, g.region
AUTHORS
Vaclav Petras, NCSU GeoForAll Lab
Michael Barton, Arizona State University (updated to GRASS 5.7)
R. Brunzema (original 5.0 Bash version)
SOURCE CODE
Available at: r.mapcalc.simple source code (history)
Accessed: unknown
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GRASS 7.8.7 r.mapcalc.simple(1grass)
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