NAME

       r.clump   -  Recategorizes  data  in  a  raster map by grouping cells that form physically
       discrete areas into unique categories.

KEYWORDS

       raster, statistics, reclass, clumps

SYNOPSIS

       r.clump
       r.clump --help
       r.clump  [-dg]  input=name   [output=name]    [title=string]     [--overwrite]    [--help]
       [--verbose]  [--quiet]  [--ui]

   Flags:
       -d
           Clump also diagonal cells
           Clumps are also traced along diagonal neighboring cells

       -g
           Print only the number of clumps in shell script style

       --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:
       input=name [required]
           Name of input raster map

       output=name
           Name for output raster map

       title=string
           Title for output raster map

DESCRIPTION

       r.clump  finds  all areas of contiguous cell category values in the input raster map. NULL
       values in the input are ignored. It assigns a unique category  value  to  each  such  area
       ("clump") in the resulting output raster map.

       Category  distinctions in the input raster map are preserved.  This means that if distinct
       category values are adjacent, they  will  NOT  be  clumped  together.  The  user  can  run
       r.reclass prior to r.clump to recategorize cells and reassign cell category values.

NOTES

       By  default, the resulting clumps are connected only by their four direct neighbors (left,
       right, top, bottom). The -d flag activates also diagonal clump tracing.

       r.clump works properly with raster map that contains only "fat" areas (more than a  single
       cell  in  width).  Linear  elements  (lines that are a single cell wide) may or may not be
       clumped together depending on the direction of the line - horizontal and vertical lines of
       cells  are  considered to be contiguous, but diagonal lines of cells are not considered to
       be contiguous and are broken up into separate clumps unless the -d flag is used.

       A random color table and other support files are generated for the output raster map.

EXAMPLES

       Perform clumping on "lakes" map (North Carolina sample dataset) and report area sizes  for
       each lake individually rather by waterbody type:
       g.region raster=lakes -p
       # report sizes by waterbody type
       r.report lakes units=h
       # clump per raster polygon
       r.clump lakes out=lakes_individual
       # report sizes by individual waterbody
       r.report lakes_individual units=h

SEE ALSO

         r.average,  r.buffer,  r.distance,  r.grow r.mapcalc, r.mfilter, r.neighbors, r.to.vect,
       r.reclass, r.statistics, r.support

AUTHOR

       Michael Shapiro, U.S. Army Construction Engineering Research Laboratory
       Markus Metz (diagonal clump tracing)

       Last changed: $Date: 2014-12-19 22:55:37 +0100 (Fri, 19 Dec 2014) $

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