[GRASSLIST:2500] statistics about areas.

[javier garcia - CEBAS]

Hi all.
I can't focus a problem in a right way. Perhaps someone could give me some 
hints.

I've got three maps:
* vector map of areas representing subwatersheds 
* raster map of soil types
* raster map of land uses
(well, I could transform the vector files into raster if it is needed)

In order to run an hydrologic model I need to know for every subwatershed, 
the area of every different combination of soil-landuse.

I've also got Postgres tables that says what kind (label) of land use 
corresponds to each code, and the same for the different soil types.

So I would like to create some kind of report that could find all 
combinations for every subwatershed and say something like:

COMBINATION   SUBWATERSHED   AREA(ha) 
soil1-landuse1       1                         45
soil1-landuse2       1                         185
soil2-landuse1        1                        54
soil1-landuse5        2                        32
...
for all watersheds

I've thought that perhaps with the help of R (or R-Postgres in someway) this 
could be possible but I can't find my way.

Thanks a lot for your ideas,

Best wishes,

Javier