NAME

       r.recode  - Recodes categorical raster maps.

KEYWORDS

       raster, recode category

SYNOPSIS

       r.recode
       r.recode help
       r.recode  [-ad]  input=name  output=name   [rules=name]    [title=string]    [--overwrite]
       [--verbose]  [--quiet]

   Flags:
       -a
           Align the current region to the input raster map

       -d
           Force output to 'double' raster map type (DCELL)

       --overwrite
           Allow output files to overwrite existing files

       --verbose
           Verbose module output

       --quiet
           Quiet module output

   Parameters:
       input=name
           Name of raster map to be recoded

       output=name
           Name for output raster map

       rules=name
           File containing recode rules
           "-" to read from stdin

       title=string
           Title for output raster map

DESCRIPTION

       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 entering rules=-.

       Rules are defined in one of these formats:
           old_low:old_high:new_low:new_high
           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:

       1      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.

       2      old-low  to old-high is reclassed to a single new value. Anything outside the range
              is null.

       3
               * to old-high will reclass everything less than old-high to a single new value.

       4
               old-low to * will reclass everything greater than old-low to a single new value.

       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.

EXAMPLES

   Map type conversion
       To simply convert a raster between formats (eg. int to float) the user would use the first
       argument. For example
           10:1500:0.1:15.0
        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.

   Value replacement
       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
           1:1:1.1:1.1
           2:2:7.5:7.5
           3:3:0.4:0.4
       EOF

AUTHOR

       CERL

       Last changed: $Date: 2010-10-31 01:46:46 -0700 (Sun, 31 Oct 2010) $

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