GRASS GIS manual: r.li.patchnum

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NAME

r.li.patchnum - Calculates patch number index on a raster map, using a 4 neighbour algorithm.

KEYWORDS

raster, landscape structure analysis, patch index

SYNOPSIS

r.li.patchnum
r.li.patchnum help
r.li.patchnum map=name conf=name output=name [--overwrite] [--verbose] [--quiet]

Flags:

--overwrite: Allow output files to overwrite existing files
--verbose: Verbose module output
--quiet: Quiet module output

Parameters:

map=name: Name of input raster map
conf=name: Configuration file
output=name: Name for output raster map

DESCRIPTION

r.li.patchnum 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.

NOTES

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

EXAMPLES

To calculate patch number index on map my_map, using my_conf configuration file (previously defined with r.li.setup) and saving results in my_out, run:

r.li.patchnum 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())"
r.li.patchnum 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() )"
r.li.patchnum map=forests conf=movwindow7 out=forests_patchnum_mov7

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

REFERENCES

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)

AUTHORS

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

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

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