[R-sig-Geo] create new raster from multiple input raster following logical conditions?

[aniruddha ghosh]

Thank you Etienne and Steven for your suggestions.

I tried the ordinary matrix method as suggested by Etienne. It works
fine. It was fast and produced excellent results for my original
raster files with 10 values.

Steven, when I try to incorporate more number of cell values, the
procedure is getting longer as I have to reclassify multiple times for
different combinations.

Best regards,


On Thu, Oct 18, 2012 at 1:50 AM, steven mosher <moshersteven at gmail.com> wrote:
>
> reclassify r1 to 1 and 0. reclassify r2 to 0 1 and 2.
> then multiply the rasters.
> so r1 becomes 0 for all values ecept 1. r2 is 1 or 2 or 0. and the product r3 will be 1 or 2 or 0
>
> On Oct 17, 2012 11:55 AM, "aniruddha ghosh" <aniru123 at gmail.com> wrote:
>>
>> Dear List,
>> I have two raster layers (r1 and r2) and the cells have values ranging 1 to
>> 10. I want to create a new raster layer from these two with different
>> conditions like:
>> 1) if r1==1 and r2==1, then r3 should be 1
>> 2) if r1==1 and r2==2, then r3 should be 2
>> else 0 etc
>>
>> With the following example:
>>
>> m1<-matrix(c(1,1,1,2,2,2,3,3,3),ncol=3,byrow=TRUE)
>> m2<-matrix(c(1,2,1,1,2,3,2,3,3),ncol=3,byrow=TRUE)
>> r1<-raster(m1)
>> r2<-raster(m2)
>> Here, r1[1,1]=1 and r2[1,1]=1, so for the new raster, [1,1] should be 1,
>> r1[1,2]=1 and r2[1,2]=2, so for the new raster, [1,2] should be 2,
>> all other cells which don't satisfy the above criteria should be zero.
>>
>> I tried with "calc" in raster package but the attempt was not successful.
>>
>> Looking forward to your suggestions!
>>
>>
>> Thanks
>> --
>> Ani
>>
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>>
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--
Ani