Hi Johannes,<br><br><div class="gmail_quote">On Fri, May 25, 2012 at 1:12 PM, Johannes Radinger <span dir="ltr"><<a href="mailto:JRadinger@gmx.at" target="_blank">JRadinger@gmx.at</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Hi,<br>
<br>
I am trying to get statistical values for a raster map in a python script.<br>
What I am doing so far is using r.univar (e.g. for the nc-dataset):<br>
<br>
grass.read_command("r.univar", map ="elevation")<br>
<br>
but how to get e.g the mean value as float? I thought of two<br>
options:<br>
<br>
1) either indexing like<br>
float(grass.read_command("r.univar", map ="elevation")[x:y])<br>
<br>
2) or splitting the string into lines and then at the ":"<br>
<br></blockquote><div><br></div><div>You can use the following:</div><div><br></div><div>import sys</div><div>import os</div><div>import grass.script as grass</div><div><br></div><div>univar = grass.read_command('r.univar', map='elevation')</div>
<div><br></div><div>print univar #so that you can see how the output looks like</div><div><br></div><div>The output is:</div><div>total null and non-null cells: 2025000</div><div>total null cells: 0</div><div><br></div><div>
Of the non-null cells:</div><div>----------------------</div><div>n: 2025000</div><div>minimum: 55.5788</div><div>maximum: 156.33</div><div>range: 100.751</div><div>mean: 110.375</div><div>mean of absolute values: 110.375</div>
<div>standard deviation: 20.3153</div><div>variance: 412.712</div><div>variation coefficient: 18.4057 %</div><div>sum: 223510266.5581016541</div><div><br></div><div>Now you want to split every line of the output with .split('\n'), you are interested in the line [10], then you split against split(':') and take the argument [1]. </div>
<div><br></div><div>mean = float(univar.split('\n')[10].split(':')[1]) </div><div><br></div><div>Hope this helps,</div><div><br></div><div>madi</div></div>-- <br>Ing. Margherita Di Leo, Ph.D.<br>