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NAME - Calculates patch number index on a raster map, using a 4 neighbour algorithm.


raster, landscape structure analysis, patch index

SYNOPSIS help map=name conf=name output=name [--overwrite] [--verbose] [--quiet]


Allow output files to overwrite existing files
Verbose module output
Quiet module output


Name of input raster map
Configuration file
Name for output raster map

DESCRIPTION calculates the "patch number index" as:
f(sample_area)= Patch_Number

This index is calculated using a 4 neighbour algorithm, diagonal cells are ignored when tracing a patch.


Do not use absolute path names for the config and output file/map parameters. If the "moving window" method was selected in, then the output will be a raster map, otherwise an ASCII file will be generated in the folder C:\Users\userxy\\output\ (MS-Windows) or $HOME/ (GNU/Linux).

If the input raster map contains only NULL values then it is considered to have zero patch.
If you want to keep NULL values, run subsequently on the resulting map:

r.null setnull=0 map=my_map
after index calculation.


To calculate patch number index on map my_map, using my_conf configuration file (previously defined with and saving results in my_out, run: map=my_map conf=my_conf out=my_out

Forest map (Spearfish sample dataset) example:

g.region rast=landcover.30m -p
r.mapcalc "forests = if(landcover.30m >= 41 && landcover.30m <= 43,1,null())" map=forests conf=movwindow7 out=forests_patchnum_mov7
r.univar forests_patchnum_mov7

Forest map (North Carolina sample dataset) example:

g.region rast=landclass96 -p
r.mapcalc "forests = if(landclass96 == 5, 1, null() )" map=forests conf=movwindow7 out=forests_patchnum_mov7

# verify
r.univar forests_patchnum_mov7 input=forests output=forests feature=area
d.mon x0
d.rast forests_patchnum_mov7
d.vect forests type=boundary

SEE ALSO - package overview


McGarigal, K., and B. J. Marks. 1995. FRAGSTATS: spatial pattern analysis program for quantifying landscape structure. USDA For. Serv. Gen. Tech. Rep. PNW-351. (PDF)


Claudio Porta and Lucio Davide Spano, students of Computer Science University of Pisa (Italy).
Commission from Faunalia Pontedera (PI) (
Markus Metz (statistics)

Last changed: $Date: 2014-10-19 14:32:22 -0700 (Sun, 19 Oct 2014) $

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