Note: A new GRASS GIS stable version has been released: GRASS GIS 7, available here. And see the new manual page here
r.recode - Recodes categorical raster maps.
raster, recode category
r.recode [-ad] input=name output=name [rules=name] [title=string] [--overwrite] [--verbose] [--quiet]
- Align the current region to the input raster map
- Force output to 'double' raster map type (DCELL)
- Allow output files to overwrite existing files
- Verbose module output
- Quiet module output
- Name of raster map to be recoded
- Name for output raster map
- File containing recode rules
- "-" to read from stdin
- Title for output raster map
r.recode creates an output raster map by recoding input
raster map based on recode rules. A title for the output
raster map may be (optionally) specified by the user.
The recode rules can be read from standard input (i.e., from the
keyboard, redirected from a file, or piped through another program) by
Rules are defined in one of these formats:
old_low:old_high:new_val (i.e. new_high == new_low)
*:old_val:new_val (interval [inf, old_val])
old_val:*:new_val (interval [old_val, inf])
r.recode is loosely based
on r.reclass and uses the GRASS
Reclass Library to convert the rasters. It has routines for converting
to every possible combination of raster (eg. CELL to DCELL, DCELL to
FCELL, etc). Standard floating point raster precision is float
(FCELL), with -d double precision (DCELL) will be written.
There are four basic routines that it accepts:
These four sets of arguments can be given on the command line, or
piped via stdin or a file. More than one set of arguments is accepted.
- old-low to old-high is reclassed to new-low to new high , where the
user provides all four values. The program figures on the fly what type of
raster should be created.
- old-low to old-high is reclassed to a single new value. Anything outside
the range is null.
- * to old-high will reclass everything less than old-high to a single
- old-low to * will reclass everything greater than old-low to a single
Map type conversion
To simply convert a raster between formats (eg. int to float) the user
would use the first argument. For example
would convert an input raster map with range between 10 and 1500 to a
float raster raster with range bewteen 0.1 and 15.0.
r.recode can be used to replace existing cell values by
others. The formatting is as described above. In following example the
values 1, 2 and 3 are replaced by 1.1, 7.5 resp. 0.4:
r.recode input=oldmap output=newmap << EOF
Last changed: $Date: 2010-10-31 01:46:46 -0700 (Sun, 31 Oct 2010) $
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