Note: This document is for an older version of GRASS GIS that will be discontinued soon. You should upgrade, and read the current manual page.
PD = Npatch / A
This index is calculated using a 4 neighbour algorithm, diagonal cells are ignored when tracing a patch.
A sample area of only NULL values is considered to have zero patches, that is, the result is always ≥ 0.
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
Available at: r.li.patchdensity source code (history)
Latest change: Mon Nov 18 20:15:32 2019 in commit: 1a1d107e4f6e1b846f9841c2c6fabf015c5f720d
Note: This document is for an older version of GRASS GIS that will be discontinued soon. You should upgrade, and read the current manual page.
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