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

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)

       Last changed: $Date: 2014-12-19 22:55:37 +0100 (Fri, 19 Dec 2014) $

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