[GRASS-user] Calculate statistics for raster values in polygons

[Micha Silver]

A. Marcia BARBOSA wrote:

> If you don't want all the nine statistics that v.rast.stats gives you
> (can be unnecessary and a bit slow for large rasters), you can use
> r.statistics instead, with method=average.
>
>   
Yes. Although I think the original post was asking to get the raster 
values into an existing vector. IIUC r.statistics would require 
converting the vector to a raster, then back to a vector. Or am I 
missing something?
>   
>>> Luis Lisboa wrote:
>>>       
>
>   
>>>    Hi all
>>>    I'm reading the v.rast.stats Help and I'm a bit confused. It says "Calculates basic univariate statistics from a raster map only for the parts covered by the specified vector map". But for >>instance if all my region is covered by different polygons and, if I want to calculate for each polygon my average value from raster, is this function helpful? (e.g. I have vector with
>>>       
>
>   
>> yes, exactly the function you need. It adds nine attribute columns to your vector layer with min,max,mean, etc values calculated from the raster.
>>     
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-- 
Micha Silver
Arava Development Co. +972-52-3665918
http://surfaces.co.il