r.mapcalc.simple1grass
Calculates a new raster map from a simple r.mapcalc expression.
Usage
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]
Keywords
raster, algebra, simple
Overview
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 format, 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 option 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 variable 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 without 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
-cflag is used).
- •
-
Option names for each map are just one letter (not amap, etc.).
- •
-
Output option name is
outputas for other modules (not outfile).
- •
-
Raster map names can be optionally quoted (the
-qflag).
- •
-
There is no expert mode (which was just running r.mapcalc).
- •
-
The
expressionoption 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=zerosr.mapcalc.simple expression="1" output=onesr.mapcalc.simple expression="2" output=twos
r.mapcalc.simple expression="A + B + C" a=zeros b=ones c=twos output=result1r.mapcalc.simple expression="(A * B) / 2 + 3 * C" a=zeros b=ones c=twos output=result2Figure: r.mapcalc.simple graphical user interface
Example expressions
Addition:
A + BNo spaces around operators are not recommended for readability, but allowed in the expression:
A+BMore complex expression with a function:
exp(A+C)+(B-2)*7Source code
Available at: r.mapcalc.simple source code (history)
Accessed: Monday Feb 24 17:51:45 2025
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© 2003-2025 GRASS Development Team, GRASS GIS 8.4.1 Reference Manual
Releases
4 releases since Debian 10 (Buster); the text changed 3 times.