This is the command r.li.patchdensitygrass that can be run in the OnWorks free hosting provider using one of our multiple free online workstations such as Ubuntu Online, Fedora Online, Windows online emulator or MAC OS online emulator
PROGRAM:
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 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\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 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
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