Tyler,
Well, that's simply brilliant. I knew it should be easy. Plus,
when I tested it I found out my rasters weren't truly mutually exclusive
after all, as some cells = 3. This is apparently an artifact of
v.to.rast polygon boundary issues but it's a pretty small problem.
Nonetheless, I have begun work on the r.update function I mentioned
in my last post. It has general utility (e.g. fixing the non-exclusive
problems I just mentioned) and seems easy enough as a crude hack. If it
shows general utility I'll post it and see if someone with GRASS coding
skills wants to take it up in C with the API.
Thanks Tyler!
On 01/01/2014 09:56 AM, Tyler Smith wrote:
Dave Roberts <[email protected]> wrote:
Colleagues,
I know this must be easy, but I haven't found it.
Suppose I have three grids (a, b, and c) where each grid is 0 or 1,
and the 1s are mutually exclusive. I want a new grid where if grid
a=1 then newgrid = 1; if grid b=1 then new grid = 2; if grid c=1 then
newgrid = 3.
Something like r.mapcalc "new=if(a,1) || if(b,2) || if(c,3)"
seems like it ought to work but I can't seem to use multiple input file
that way.
Thanks in advance for any help, Dave
What about
r.mapcalc new=a + b*2 + c*3
If the maps are mutually exclusive, only one of the three will be
non-zero for each cell.
Tyler
--
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David W. Roberts office 406-994-4548
Professor and Head FAX 406-994-3190
Department of Ecology email [email protected]
Montana State University
Bozeman, MT 59717-3460
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