|
@@ -1,8 +1,8 @@
|
|
|
<h2>DESCRIPTION</h2>
|
|
|
|
|
|
-<em>r.univar</em> calculates the univariate statistics of a raster map.
|
|
|
-This includes the number of cells counted, minimum and maximum cell values,
|
|
|
-range, arithmetic mean, population variance, standard deviation, and
|
|
|
+<em>r.univar</em> calculates the univariate statistics of one or several raster
|
|
|
+map(s). 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,
|
|
@@ -13,23 +13,31 @@ 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.
|
|
|
+<p>
|
|
|
+When multiple input maps are given to <em>r.univar</em>, the overall statistics
|
|
|
+are calculated. This is useful for a time series of the same variable, as well as
|
|
|
+for the case of a segmented/tiled dataset. Allowing multiple raster maps to be
|
|
|
+specified saves the user from using a temporary raster map for the result of
|
|
|
+<em>r.series</em> or <em>r.patch</em>.
|
|
|
|
|
|
<h2>NOTES</h2>
|
|
|
|
|
|
-As with most GRASS raster modules, <em>r.univar</em> operates on the cell
|
|
|
+As with most GRASS raster modules, <em>r.univar</em> operates on the raster
|
|
|
array defined by the current 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>
|
|
|
+<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.
|
|
|
-<p>Without a <b>zones</b> input raster, the <em>r.quantile</em> module will
|
|
|
+<p>
|
|
|
+Without a <b>zones</b> input raster, the <em>r.quantile</em> module will
|
|
|
be significantly more efficient for calculating percentiles with large maps.
|
|
|
|
|
|
<h2>EXAMPLE</h2>
|
|
|
|
|
|
Calculate the raster statistics for zones within a vector map coverage
|
|
|
-and upload the results for mean, min and max back to the vector map.
|
|
|
+and upload the results for mean, min and max back to the vector map:
|
|
|
|
|
|
<div class="code"><pre>
|
|
|
#### set the raster region to match the map
|
|
@@ -106,15 +114,15 @@ v.db.select fields_stats
|
|
|
<h2>SEE ALSO</h2>
|
|
|
|
|
|
<em>
|
|
|
-<a href="g.region.html">g.region</a><br>
|
|
|
-<a href="r3.univar.html">r3.univar</a><br>
|
|
|
-<a href="r.mode.html">r.mode</a><br>
|
|
|
-<a href="r.quantile.html">r.quantile</a><br>
|
|
|
-<a href="r.series.html">r.series</a><br>
|
|
|
-<a href="r.stats.html">r.stats</a><br>
|
|
|
-<a href="r.statistics.html">r.statistics</a><br>
|
|
|
-<a href="v.rast.stats.html">v.rast.stats</a><br>
|
|
|
-<a href="v.univar.html">v.univar</a><br>
|
|
|
+<a href="g.region.html">g.region</a>,
|
|
|
+<a href="r3.univar.html">r3.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="r.stats.html">r.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>
|
|
|
|
|
|
|
|
@@ -122,6 +130,7 @@ v.db.select fields_stats
|
|
|
|
|
|
Hamish Bowman, Otago University, New Zealand<br>
|
|
|
Extended statistics by Martin Landa<br>
|
|
|
+Multiple input map support by Ivan Shmakov<br>
|
|
|
Zonal loop by Markus Metz
|
|
|
|
|
|
<p><i>Last changed: $Date$</i>
|