[GRASS-SVN] r66083 - grass/trunk/raster/r.univar
svn_grass at osgeo.org
svn_grass at osgeo.org
Wed Sep 2 04:26:35 PDT 2015
Author: martinl
Date: 2015-09-02 04:26:35 -0700 (Wed, 02 Sep 2015)
New Revision: 66083
Added:
grass/trunk/raster/r.univar/runivar_basins.png
grass/trunk/raster/r.univar/runivar_basins_elev_zonal.png
Modified:
grass/trunk/raster/r.univar/r.univar.html
Log:
r.univar: manual extended (by Ludmila Furtkevicova)
Modified: grass/trunk/raster/r.univar/r.univar.html
===================================================================
--- grass/trunk/raster/r.univar/r.univar.html 2015-09-02 11:17:37 UTC (rev 66082)
+++ grass/trunk/raster/r.univar/r.univar.html 2015-09-02 11:26:35 UTC (rev 66083)
@@ -13,6 +13,7 @@
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
@@ -25,6 +26,7 @@
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>
extended statistics flag is used with a very large region setting. If the
@@ -33,6 +35,7 @@
<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.
+
<p>
For calculating univariate statistics from a raster map based on vector polygon
map and uploads statistics to new attribute columns, see
@@ -40,24 +43,124 @@
<h2>EXAMPLE</h2>
-Calculate the raster statistics for zones within a raster polygon map
-coverage (basins, North Carolina sample dataset):
+In this example, the raster polygon map <tt>basins</tt> in the North
+Carolina sample dataset is used to calculate raster statistics for zones
+for <tt>elevation</tt> raster map:
<div class="code"><pre>
-# set computational region
-g.region raster=basin -p
+g.region raster=basins -p
+</pre></div>
-# check basin IDs
-r.category basin
+This will set and print computational region in the format:
-#### perform analysis with elevation map (extent and res. match)
-r.univar -t map=elevation zones=basin separator=comma \
+<div class="code"><pre>
+projection: 99 (Lambert Conformal Conic)
+zone: 0
+datum: nad83
+ellipsoid: a=6378137 es=0.006694380022900787
+north: 228500
+south: 215000
+west: 630000
+east: 645000
+nsres: 10
+ewres: 10
+rows: 1350
+cols: 1500
+cells: 2025000
+</pre></div>
+
+Check basin's IDs using:
+
+<div class="code"><pre>
+r.category basins
+</pre></div>
+
+This will print them in the format:
+
+<div class="code"><pre>
+2
+4
+6
+8
+10
+12
+14
+16
+18
+20
+22
+24
+26
+28
+30
+</pre></div>
+
+Visualization of them underlying elevation map can be created as:
+
+<div class="code"><pre>
+d.mon wx0
+d.rast map=elevation
+r.colors map=elevation color=grey
+d.rast map=basins
+r.colors map=basins color=bgyr
+d.legend raster=basins use=2,4,6,8,10,12,14,16,18,20,22,24,26,28,30
+d.barscale
+</pre></div>
+
+<!--
+g.region -a n=227228 s=220895 w=631362 e=641170
+d.out.file runivar_basins.png
+optipng -o5 runivar_basins.png width=200px
+-->
+
+<center>
+<img src="runivar_basins.png" alt="Basins and their IDs" align="middle"
+width="600">
+<p>
+Figure: Zones (basins, opacity: 60%) with underlying elevation map
+for North Carolina sample dataset.
+</center>
+
+<p>
+Then statistics for elevation can be calculated separately for every
+zone, i.e. basin found in the <b>zones</b> parameter:
+
+<div class="code"><pre>
+r.univar -t map=elevation zones=basins separator=comma \
output=basin_elev_zonal.csv
</pre></div>
+This will print information in the format:
+
+<div class="code"><pre>
+zone,label,non_null_cells,null_cells,min,max,range,mean,mean_of_abs,
+stddev,variance,coeff_var,sum,sum_abs2,,116975,0,55.5787925720215,
+133.147018432617,77.5682258605957,92.1196971445722,92.1196971445722,
+15.1475301152556,229.447668592576,16.4433129773355,10775701.5734863,
+10775701.57348634,,75480,0,61.7890930175781,110.348838806152,
+48.5597457885742,83.7808205765268,83.7808205765268,11.6451777476995,
+135.610164775515,13.8995747088232,6323776.33711624,6323776.33711624
+6,,1137,0,66.9641571044922,83.2070922851562,16.2429351806641,
+73.1900814395257,73.1900814395257,4.15733292896409,17.2834170822492,
+5.68018623179036,83217.1225967407,83217.12259674078,,80506,
+0,67.4670791625977,147.161514282227, ...
+</pre></div>
+
+Comma Separated Values (CSV) file is best viewed through a spreadsheet
+program such as Microsoft Excel, Libre/Open Office Calc or Google Docs:
+
+<p>
+<center>
+<img src="runivar_basins_elev_zonal.png" alt="TABLE" align="middle"
+width="900">
+<p>
+Figure: Raster statistics for zones (basins, North Carolina sample
+dataset) viewed through Libre/Open Office Calc
+</center>
+
<h2>TODO</h2>
-<i>mode, skewness, kurtosis</i>
+To be implemented <i>mode, skewness, kurtosis</i>.
<h2>SEE ALSO</h2>
Added: grass/trunk/raster/r.univar/runivar_basins.png
===================================================================
(Binary files differ)
Property changes on: grass/trunk/raster/r.univar/runivar_basins.png
___________________________________________________________________
Added: svn:mime-type
+ image/png
Added: grass/trunk/raster/r.univar/runivar_basins_elev_zonal.png
===================================================================
(Binary files differ)
Property changes on: grass/trunk/raster/r.univar/runivar_basins_elev_zonal.png
___________________________________________________________________
Added: svn:mime-type
+ image/png
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