To redefine a map's category, type:
r.reclass input=mapname output=re
1=2
end
This will reclass everything to 0, and all 1's will become 2's.
Then, type:
r.mapcalc newlayer=re+0
(watch your region and mask settings !)
You can then delete re
And newlayer will have only a category of 2.
Nancy :~)
Lower MS Valley Division
Vicksburg, MS 39180