Geografic-Information-System/raster/r.univar/r3.univar.html

<h2>DESCRIPTION</h2>

<em>r3.univar</em> calculates the univariate statistics for raster3d maps.
This includes the number of cells counted, minimum and maximum cell values,
range, arithmetic mean, population variance, standard deviation, and 
coefficient of variation. Statistics are calculated separately for every
category/zone found in the <b>zones</b> input map if given.
If the <b>-e</b> extended statistics flag is given the 1st quartile, median,
3rd quartile, and given <b>percentile</b> are calculated.
If the <b>-g</b> flag is given the results are presented in a format suitable
for use in a shell script.
If the <b>-t</b> flag is given the results are presented in tabular format
with the given field separator. The table can immediately be converted to a
vector attribute table which can then be linked to a vector, e.g. the vector
that was rasterized to create the <b>zones</b> input raster.

<h2>NOTES</h2>

As with most GRASS raster3d modules, <em>r3.univar</em> operates on the voxel
array defined by the current 3d region settings, not the original extent and
resolution of the input map. See <em><a href="g.region.html">g.region</a></em>.
<p>
This module can use large amounts of system memory when the <b>-e</b>
extended statistics flag is used with a very large region setting. If the
region is too large the module should exit gracefully with a memory allocation
error. Basic statistics can be calculated using any size input region.

<!-- no rast3D support?
<p>
The <em>r.quantile</em> module will be significantly more efficient for
calculating percentiles with large maps.
-->

<h2>TODO</h2>

<i>mode, skewness, kurtosis</i>



<h2>SEE ALSO</h2>

<em>
<a href="g.region.html">g.region</a>,
<a href="r.univar.html">r.univar</a>,
<a href="r.mode.html">r.mode</a>,
<a href="r.quantile.html">r.quantile</a>,
<a href="r.series.html">r.series</a>,
<a href="r3.stats.html">r3.stats</a>,
<a href="r.statistics.html">r.statistics</a>,
<a href="v.rast.stats.html">v.rast.stats</a>,
<a href="v.univar.html">v.univar</a>
</em>


<h2>AUTHORS</h2>

Soeren Gebbert<br>
Code is based on r.univar from<br>
Hamish Bowman, Otago University, New Zealand<br>
and Martin Landa<br>
Zonal loop by Markus Metz


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