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

Pedro Roma pedroroma1982 at gmail.com
Mon Jan 18 06:42:45 EST 2010

Greetings all
As far as I can see, r.statistics (
http://grass.itc.it/grass64/manuals/html64_user/r.statistics.html) uses as
cover and as basis a RASTER map. But, "All cells in the base layer are
considered one object for the analysis". This is not what I want because I
want base layer to be a polygon not a cell. Or Am I reading this wrong?

On Sat, Jan 16, 2010 at 9:59 AM, Markus Metz <
markus.metz.giswork at googlemail.com> wrote:

> 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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