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 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 -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: Thursday Aug 01 11:31:52 2024

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       © 2003-2024 GRASS Development Team, GRASS GIS 8.4.0 Reference Manual