> my apologies to everyone taking the time to answer this question. i
> didn't explain myself very well.
>
> i have the indices of the elements of the matrix and the matrix won't
> necessarily have zeros everywhere else. is there a way to use the
> indices to strip the elements i need?
>
RTFM ?"[".
> x <- matrix(c(0, 2, 0, 0, 0, 4, 3, 0, 0), nrow=3)
> x
[,1] [,2] [,3]
[1,] 0 0 3
[2,] 2 0 0
[3,] 0 4 0
> ?"["
> xx <- matrix(c(1, 2, 3, 3, 1, 2), ncol=2)
> xx
[,1] [,2]
[1,] 1 3
[2,] 2 1
[3,] 3 2
> x[xx]
[1] 3 2 4
>
HTH,
Ray
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