r.li.patchdensity(1grass) GRASS GIS User's Manual r.li.patchdensity(1grass)
NAME
r.li.patchdensity - Calculates patch density index on a raster map,
using a 4 neighbour algorithm
KEYWORDS
raster, landscape structure analysis, patch index
SYNOPSIS
r.li.patchdensity
r.li.patchdensity --help
r.li.patchdensity input=name config=name output=name [--overwrite]
[--help] [--verbose] [--quiet] [--ui]
Flags:
--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
config=name [required]
Configuration file
output=name [required]
Name for output raster map
DESCRIPTION
r.li.patchdensity calculates the "patch density index", the number of
patches per square kilometer, as:
PD = Npatch / A
with:
• A:sampling area size
• Npatch: number of patches
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 pa-
rameters. If the "moving window" method was selected in
g.gui.rlisetup, then the output will be a raster map, otherwise an
ASCII file will be generated in the folder C:\Users\userxy\App-
Data\Roaming\GRASS7\r.li\output\ (MS-Windows) or
$HOME/.grass7/r.li/output/ (GNU/Linux).
A sample area of only NULL values is considered to have zero patches,
that is, the result is always ≥ 0.
EXAMPLES
To calculate patch density index on map my_map, using my_conf configu-
ration file (previously defined with g.gui.rlisetup) and saving results
in my_out, run:
r.li.patchdensity input=my_map conf=my_conf output=my_out
Example for Spearfish forest areas:
g.region raster=landcover.30m -p
# extract forested areas:
r.category landcover.30m
r.mapcalc "forests = if(landcover.30m >= 41 && landcover.30m <= 43, 1, null())"
# patch density (7x7 moving window defined in g.gui.rlisetup):
r.li.patchdensity forests conf=movwindow7 out=forests_p_dens7
r.univar forests_p_dens7
d.rast.leg forests_p_dens7
r.to.vect forests out=forests feature=area
d.vect forests type=boundary
Forest map (North Carolina sample dataset) example:
g.region raster=landclass96 -p
r.mapcalc "forests = if(landclass96 == 5, 1, null() )"
r.li.patchdensity input=forests conf=movwindow7 out=forests_patchdensity_mov7
# verify
r.univar forests_patchdensity_mov7
r.to.vect input=forests output=forests type=area
d.mon wx0
d.rast forests_patchdensity_mov7
d.vect forests type=boundary
SEE ALSO
r.li - package overview
g.gui.rlisetup
REFERENCES
McGarigal, K., and B. J. Marks. 1995. FRAGSTATS: spatial pattern analy-
sis program for quantifying landscape structure. USDA For. Serv. Gen.
Tech. Rep. PNW-351. (PDF)
AUTHORS
Michael Shapiro - CERL (patch identification)
Markus Metz (statistics)
SOURCE CODE
Available at: r.li.patchdensity source code (history)
Accessed: unknown
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GRASS 7.8.7 r.li.patchdensity(1grass)
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