[GRASS-user] Change value of cells in raster map

[Helmut Kudrnovsky]

Rich Shepard wrote
> On Thu, 8 Jun 2017, Helmut Kudrnovsky wrote:
> 
>> raster A:
>> raster B: raster eg with values 1 and 2
>>
>> in R.mapcalc :
>>
>> if(B==1, A, A/B)
>>
>> which means in the resulting map: if the cell value in B is equal to 1,
>> then
>> take the raster cell value of raster A, otherwise divide the raster cell
>> value of A by the raster cell value of B.
> 
> Helmut,
> 
>    I understand this produces a new map from two maps with different
> values.
> My two raster maps have the same value (2) because they come from dividing
> a
> single vector map whose area has a single value.
> 
>    I'm trying various v.db.* modules to change values in the two vector
> maps,
> then I can recreate the vector maps from these and each will have the
> desired value. So far no success, but I'll keep trying.
> 
> Thanks,
> 
> Rich
> 
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https://grass.osgeo.org/grass73/manuals/v.db.update.html

?

-Add e.g. a integer column to the vector 
- Insert 1 and 2 for the polygons in this column by v.db.update 
- V.to.rast by attributes 
- R.mapcalc 



-----
best regards
Helmut
--
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