r.mapcalc.simple(1)

📦
version 8.4.2 · 8 versions
, in fedora 44

r.mapcalc.simple 💖

okay bestie, gather round, because this is the GRASS GIS User's Manual page for r.mapcalc.simple(1) and honestly? it's giving ✨convenience✨ in the best way.

🌸 NAME 🌸

r.mapcalc.simple — Calculates a new raster map from a simple r.mapcalc expression. literally that's the whole gig 🫶

🏷️ 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 (and heads up bestie: the result is non-deterministic, so like, don't expect the same thing twice 💀)
  • -q — Quote the map names
  • -c — Case sensitive variable names
  • --overwrite — Allow output files to overwrite existing files (iconic but dangerous energy)
  • --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 💅

So r.mapcalc.simple provides a wrapper to r.mapcalc. Up to 6 maps can be combined using simple expressions. no cap.

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. cute, right?

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. so like, know your lane, bestie 💜

📝 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 -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 outfile).
  • 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 allowed 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: Saturday Jan 17 05:41:52 2026

Main index | Raster index | Topics index | Keywords index | Graphical index | Full index

© 2003-2025 GRASS Development Team, GRASS GIS 8.4.2 Reference Manual

okay that's the whole page, bestie, you ate that 💅✨ so anyway, this was the GRASS 8.4.2 manual for r.mapcalc.simple(1) — go forth and calculate some rasters, periodt. 🎀🦋💖

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