[R] Row comparisons to a new matrix?

Gabor Grothendieck ggrothendieck at gmail.com
Fri Oct 6 23:28:33 CEST 2006


There is a generalized inner product here:

http://tolstoy.newcastle.edu.au/R/help/05/04/3709.html

On 10/6/06, Atte Tenkanen <attenka at utu.fi> wrote:
> Hi,
> Can somebody tell me, which is the fastest way to make comparisons between all rows in a matrix (here A) and put the results to the new symmetric matrix? I have here used cosine distance as an example, but the comparison function can be any other, euclidean dist etc.
>
> A=rbind(c(2,3),c(4,5),c(-1,2),c(5,6))
>
> M=matrix(nrow=length(A[,1]),ncol=length(A[,1]))
>
> for(i in 1:length(A[,1]))
> {
>        for(j in 1:length(A[,1]))
>        {
>                M[i,j]=cosine(A[i,],A[j,])
>        }
> }
>
> Atte Tenkanen
> University of Turku, Finland
>
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