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r.li.patchdensity(1grass)

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 &#8805; 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

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 22:17:36 +0100 (Fri, 19 Dec 2014) $

SOURCE CODE

   Available at: r.li.patchdensity source code (history)

   Main  index  | Raster index | Topics index | Keywords index | Graphical
   index | Full index

    2003-2016 GRASS Development Team, GRASS GIS 7.2.0 Reference Manual

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