GRASS GIS manual: r.li.cwed

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NAME

r.li.cwed - Calculates contrast weighted edge density index on a raster map

KEYWORDS

raster, landscape structure analysis, patch index

SYNOPSIS

r.li.cwed
r.li.cwed help
r.li.cwed map=name conf=name path=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
path=name: Name of file that contains the weight to calculate the index
output=name: Name for output raster map

DESCRIPTION

r.li.cwed (contrast weighted edge density) calculates the edge density between patch types specified:

rlicwed formula

with:

k: attribute
m: number of non-null attributes in the sampling area
eik: total length of edge in landscape between patch types i and k
dik: dissimilarity (edge contrast weight) between patch types i and k
Area: total landscape area

The input file contains a row for each couple of patch type that we want to consider in the calculation. Each row must be saved using this syntax:
patchType1,patchType2,dissimilarityBetweenPatchType1andPatchType2

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 sample area contains only NULL values it is considered to have 0 patch and CWED=0. If Area is 0 r.li.cwed returns -1. This is only possible if the map is masked.
If you want to change these -1 values to NULL, run subsequently on the resulting map:

r.null setnull=-1 map=my_map

after index calculation.

EXAMPLES

To calculate the contrast weighted edge density 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.cwed map=my_map conf=my_conf output=my_out \
          path=/path/to/weights.csv

Example for input "weights.csv" file:

12,16,0.65
44,123,0.32
56,12,0.54
23,66,0.99

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

Serena Pallecchi student of Computer Science University of Pisa (Italy).
Commission from Faunalia Pontedera (PI), Italy (www.faunalia.it)
Markus Metz

Last changed: $Date: 2014-08-18 13:13:41 -0700 (Mon, 18 Aug 2014) $

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