r.li.patchdensity
Calculates patch density index on a raster map, using a 4 neighbour algorithm
r.li.patchdensity input=name config=name output=name [--overwrite] [--verbose] [--quiet] [--qq] [--ui]
Example:
r.li.patchdensity input=name config=name output=name
grass.script.run_command("r.li.patchdensity", input, config, output, overwrite=False, verbose=False, quiet=False, superquiet=False)
Example:
gs.run_command("r.li.patchdensity", input="name", config="name", output="name")
Parameters
input=name [required]
Name of input raster map
config=name [required]
Configuration file
output=name [required]
Name for output raster map
--overwrite
Allow output files to overwrite existing files
--help
Print usage summary
--verbose
Verbose module output
--quiet
Quiet module output
--qq
Very quiet module output
--ui
Force launching GUI dialog
input : str, required
Name of input raster map
Used as: input, raster, name
config : str, required
Configuration file
Used as: input, file, name
output : str, required
Name for output raster map
Used as: output, raster, name
overwrite: bool, optional
Allow output files to overwrite existing files
Default: False
verbose: bool, optional
Verbose module output
Default: False
quiet: bool, optional
Quiet module output
Default: False
superquiet: bool, optional
Very quiet module output
Default: False
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 parameters. 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\AppData\Roaming\GRASS8\r.li\output\
(MS-Windows) or
$HOME/.grass8/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 configuration 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 analysis 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)
Latest change: Friday Feb 07 19:16:09 2025 in commit a82a39f