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=None, verbose=None, quiet=None, superquiet=None)
Example:
gs.run_command("r.li.patchdensity", input="name", config="name", output="name")
grass.tools.Tools.r_li_patchdensity(input, config, output, overwrite=None, verbose=None, quiet=None, superquiet=None)
Example:
tools = Tools()
tools.r_li_patchdensity(input="name", config="name", output="name")
This grass.tools API is experimental in version 8.5 and expected to be stable in version 8.6.
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: None
verbose : bool, optional
Verbose module output
Default: None
quiet : bool, optional
Quiet module output
Default: None
superquiet : bool, optional
Very quiet module output
Default: None
input : str | np.ndarray, required
Name of input raster map
Used as: input, raster, name
config : str | io.StringIO, required
Configuration file
Used as: input, file, name
output : str | type(np.ndarray) | type(np.array) | type(gs.array.array), required
Name for output raster map
Used as: output, raster, name
overwrite : bool, optional
Allow output files to overwrite existing files
Default: None
verbose : bool, optional
Verbose module output
Default: None
quiet : bool, optional
Quiet module output
Default: None
superquiet : bool, optional
Very quiet module output
Default: None
Returns:
result : grass.tools.support.ToolResult | np.ndarray | tuple[np.ndarray] | None
If the tool produces text as standard output, a ToolResult object will be returned. Otherwise, None
will be returned. If an array type (e.g., np.ndarray) is used for one of the raster outputs, the result will be an array and will have the shape corresponding to the computational region. If an array type is used for more than one raster output, the result will be a tuple of arrays.
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: Tuesday Apr 29 06:19:47 2025 in commit 12f893b