[GRASS-user] newbie category question..

[Nikos Alexandris]

On Mon, 2008-03-10 at 15:50 -0700, cgnicholas at alamedanet.net wrote:
> Hi -
> 
Hi Chris!

> I'm trying to do something I thought was fairly simple, but eludes me...
it took me a while till I understand how to do what other people told
me... on a similar problem. But since then I know where to look at
least ;-)
> 
> I'm trying to find the average elevation of polygons.
Try with v.rast.stats

or with

"starspan" which is created to handle raster vs vector statistical
problems like the one you have. Have a look at the user guide of it:
http://starspan.casil.ucdavis.edu/doku/doku.php?id=userguide

> I used
> gdal_rasterize to make a layer, which does indeed have unique categories,
> and values, for each building.
> 
> I'm trying to use this layer against a DEM, and on a per-polygon basis,
> get the min/max of the DEM ... I was thinking that somehow I might use
> r.statistics, but....not so straightforward, apparently.
> 
> thanks in advance for any suggestions!
> 
> Chris

Cheers,

Nikos
> 
> p.s. - it would sure be nice if I could make key/value pairs within
> mapcalc; that way I could read a category from one layer, make a key, and
> fetch it anywhere within mapcalc...
I don't understand here.
> 
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