[GRASS-user] Aggregate a classification map according to a vector file

Markus Metz markus.metz.giswork at googlemail.com
Sat Jan 16 04:59:18 EST 2010

Markus Neteler wrote:
> Pedro Roma wrote:
>> Greetings all
>> A few emails that people sent, regarding classigication operations GRASS
>> were extremely helpful :)
>> But now, I have one question:
>> I need to do some aggregation of the classification map according to regions
>> specified in a vector file. What I mean is, for each county I need to have
>> an aggregation of all classified pixels in order to have only one value that
>> represents that county.
>> E.g. I have a land cover classification for my region and now I need to
>> aggregate the classified map according to my counties in order to have a
>> vector map in which each county is represented by its more frequent
>> classification.
>> Is this possible in GRASS? Was I clear :D ?
> Could this be of interest?
> Addons: r.univar.zonal
> http://svn.osgeo.org/grass/grass-addons/raster/r.univar2.zonal/r.univar.zonal.html
Or r.statistics with method=mode, gives you the most frequent value in 
cover map for each value in base map. AFAIK, r.univar[.zonal] doesn't 
have modal as output.

Markus M

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