.TH r.li.patchdensity 1grass "" "GRASS 8.3.1" "GRASS GIS User's Manual"
.SH NAME
\fI\fBr.li.patchdensity\fR\fR  \- Calculates patch density index on a raster map, using a 4 neighbour algorithm
.SH KEYWORDS
raster, landscape structure analysis, patch index
.SH SYNOPSIS
\fBr.li.patchdensity\fR
.br
\fBr.li.patchdensity \-\-help\fR
.br
\fBr.li.patchdensity\fR \fBinput\fR=\fIname\fR \fBconfig\fR=\fIname\fR \fBoutput\fR=\fIname\fR  [\-\-\fBoverwrite\fR]  [\-\-\fBhelp\fR]  [\-\-\fBverbose\fR]  [\-\-\fBquiet\fR]  [\-\-\fBui\fR]
.SS Flags:
.IP "\fB\-\-overwrite\fR" 4m
.br
Allow output files to overwrite existing files
.IP "\fB\-\-help\fR" 4m
.br
Print usage summary
.IP "\fB\-\-verbose\fR" 4m
.br
Verbose module output
.IP "\fB\-\-quiet\fR" 4m
.br
Quiet module output
.IP "\fB\-\-ui\fR" 4m
.br
Force launching GUI dialog
.SS Parameters:
.IP "\fBinput\fR=\fIname\fR \fB[required]\fR" 4m
.br
Name of input raster map
.IP "\fBconfig\fR=\fIname\fR \fB[required]\fR" 4m
.br
Configuration file
.IP "\fBoutput\fR=\fIname\fR \fB[required]\fR" 4m
.br
Name for output raster map
.SH DESCRIPTION
\fIr.li.patchdensity\fR calculates the \(dqpatch density index\(dq,
the number of patches per square kilometer, as:
.br
.nf
\fC
PD = Npatch / A
\fR
.fi
with:
.RS 4n
.IP \(bu 4n
\fBA\fR:sampling area size
.IP \(bu 4n
\fBNpatch\fR: number of patches
.RE
.PP
This index is calculated using a 4 neighbour algorithm, diagonal cells
are ignored when tracing a patch.
.SH NOTES
Do not use absolute path names for the \fBconfig\fR and \fBoutput\fR
file/map parameters.
If the \(dqmoving window\(dq method was selected in \fBg.gui.rlisetup\fR, then the
output will be a raster map, otherwise an ASCII file will be generated in
the folder C:\(rsUsers\(rsuserxy\(rsAppData\(rsRoaming\(rsGRASS8\(rsr.li\(rsoutput\(rs
(MS\-Windows) or $HOME/.grass8/r.li/output/ (GNU/Linux).
.PP
A sample area of only NULL values is considered to have zero patches,
that is, the result is always ≥ 0.
.SH EXAMPLES
To calculate patch density index on map \fImy_map\fR, using
\fImy_conf\fR configuration file (previously defined with
\fIg.gui.rlisetup\fR) and saving results in \fImy_out\fR, run:
.br
.nf
\fC
r.li.patchdensity input=my_map conf=my_conf output=my_out
\fR
.fi
.PP
Example for Spearfish forest areas:
.br
.nf
\fC
g.region raster=landcover.30m \-p
# extract forested areas:
r.category landcover.30m
r.mapcalc \(dqforests = if(landcover.30m >= 41 && landcover.30m <= 43, 1, null())\(dq
# 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
\fR
.fi
.PP
Forest map (North Carolina sample dataset) example:
.br
.nf
\fC
g.region raster=landclass96 \-p
r.mapcalc \(dqforests = if(landclass96 == 5, 1, null() )\(dq
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
\fR
.fi
.SH SEE ALSO
\fI
r.li \- package overview
.br
g.gui.rlisetup
\fR
.SH 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)
.SH AUTHORS
Michael Shapiro \- CERL (patch identification)
.br
Markus Metz (statistics)
.SH SOURCE CODE
.PP
Available at:
r.li.patchdensity source code
(history)
.PP
Accessed: Sunday Dec 17 17:21:53 2023
.PP
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.PP
© 2003\-2023
GRASS Development Team,
GRASS GIS 8.3.1 Reference Manual