[R] matrix similarity comparison

[Matthew Keller]

hi Carlos,

its not really clear what you're asking here. If all you want is to
see what entries are the same and which are different between two
matrices of the same dimensions, then this does it:
#same
m1==m2
#diff
m1 != m2

If you want to extract the ones that are the same,
indx <- m1==m2
> indx
      [,1] [,2]  [,3]  [,4]
[1,]  TRUE TRUE FALSE  TRUE
[2,]  TRUE TRUE  TRUE FALSE
[3,] FALSE TRUE FALSE  TRUE
> m1[indx]
1 0 0 1 0 1 1 1


On 3/19/07, Carlos Guerra <carlosguerra at esa.ipvc.pt> wrote:
> Good morning to you all,
>
> I have a problem with a set of matrices that I want to compare.
>
> I want to see the similarity between them, and to be able to extract the
> differences between them.
>
> They have all the same number of columns and rows, and correspond
> presence absence data:
>
> for example:
>
> m1 <- matrix(c(1,0,0,0,1,0,1,1,1,1,1,1), 3,4)
> m2 <- matrix(c(1,0,1,0,1,0,0,1,0,1,0,1), 3,4)
>
> I tried with the function cor2m() [package=edodist] but it didn't worked
> and my matrices are much bigger than the ones from the example.
>
> Thank you,
>
> Carlos
>
> --
> Carlos GUERRA
>
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-- 
Matthew C Keller
Postdoctoral Fellow
Virginia Institute for Psychiatric and Behavioral Genetics