Geografic-Information-System/raster/r.li/r.li.mpa/r.li.mpa.html

<h2>DESCRIPTION</h2>

<em>r.li.mpa</em> (mean pixel attribute) calculates the average value of the
attribute of all the non-null cells in the sampling area as:<br>
<img src="rlimpa_formula.png" alt="rlimpa formula"> <br>
with:<br>
<ul>
  <li><b>i</b>: attribute</li>
  <li><b>m</b>: number of non-null attributes in the sampling area </li>
  <li><b>w<small><small>i</small></small></b>: number of cells of attribute i</li>
  <li><b>size</b>: size of sampling area (in cells)</li>
</ul>

<h2>NOTES</h2>

Do not use absolute path names for the <b>config</b> and <b>output</b>
file/map parameters.

If the "moving window" method was selected in <b>g.gui.rlisetup</b>, then the
output will be a raster map, otherwise an ASCII file will be generated in
the folder <tt>C:\Users\userxy\AppData\Roaming\GRASS7\r.li\output\</tt>
(MS-Windows) or <tt>$HOME/.grass7/r.li/output/</tt> (GNU/Linux).
<p>
<!-- TODO: verify next: -->
If the input raster map contains only NULL values then <em>r.li.mpa</em> considers to
have 0 patches.<br>
If area is 0 <em>r.li.mpa</em> returns -1; it is possible only if the
raster is masked <br>
If you want to change these -1 values to NULL, run subsequently on the resulting map:
<div class="code"><pre>
r.null setnull=-1 input=my_map
</pre></div>
after index calculation.

<h2>EXAMPLES</h2>
To calculate the mean pixel attribute index on map <em>my_map</em>, using
<em>my_conf</em> configuration file (previously defined with
<em>g.gui.rlisetup</em>) and saving results in <em>my_out</em>, run:
<div class="code"><pre>
r.li.mpa input=my_map conf=my_conf output=my_out
</pre></div>
<p>

Forest map (Spearfish sample dataset) example:
<div class="code"><pre>
g.region raster=landcover.30m -p
r.mapcalc "forests = if(landcover.30m >= 41 && landcover.30m <= 43,1,null())"
r.li.mpa input=forests conf=movwindow7 out=forests_mpa_mov7
r.univar forests_mpa_mov7
</pre></div>
<p>

Forest map (North Carolina sample dataset) example:
<div class="code"><pre>
g.region raster=landclass96 -p
r.mapcalc "forests = if(landclass96 == 5, 1, null() )"
r.li.mpa input=forests conf=movwindow7 out=forests_mpa_mov7

# verify
r.univar forests_mpa_mov7
r.to.vect input=forests output=forests type=area
d.mon wx0
d.rast forests_mpa_mov7
d.vect forests type=boundary
</pre></div>

<h2>SEE ALSO</h2>
<em>
<a href="r.li.html">r.li</a> - package overview<br>
<a href="g.gui.rlisetup.html">g.gui.rlisetup</a>
</em>

<h2>REFERENCES</h2>
McGarigal, K., and B. J. Marks. 1995. FRAGSTATS: spatial pattern
analysis program for quantifying landscape structure. USDA For. Serv.
Gen. Tech. Rep. PNW-351. (<a href="http://treesearch.fs.fed.us/pubs/3064">PDF</a>)

<h2>AUTHORS</h2>
Serena Pallecchi student of Computer Science University of Pisa (Italy).<br>
Commission from Faunalia Pontedera (PI), Italy (www.faunalia.it)<br>
Markus Metz

<p>
<i>Last changed: $Date$</i>