On Wed, 2005-04-13 at 21:09 -0500, Chris Bergstresser wrote:
> Hi all --
>
> Quick (I hope) question: I've got a correlation matrix. Is there a
> quick way to find all the row/column names for those correlations higher
> than some value, like 0.4?
> mat <- cor(matrix(rnorm(100), ncol = 5))
> mat
[,1] [,2] [,3] [,4] [,5]
[1,] 1.00000000 0.08406738 -0.18412634 -0.15484250 0.18975606
[2,] 0.08406738 1.00000000 0.06242012 0.44583819 -0.03338074
[3,] -0.18412634 0.06242012 1.00000000 0.01045560 0.16876206
[4,] -0.15484250 0.44583819 0.01045560 1.00000000 0.26283234
[5,] 0.18975606 -0.03338074 0.16876206 0.26283234 1.00000000
# Get row/col positions
> which(mat > 0.4, arr.ind = TRUE)
row col
[1,] 1 1
[2,] 2 2
[3,] 4 2
[4,] 3 3
[5,] 2 4
[6,] 4 4
[7,] 5 5
# Get the actual values
> mat[which(mat > 0.4, arr.ind = TRUE)]
[1] 1.0000000 1.0000000 0.4458382 1.0000000 0.4458382 1.0000000
[7] 1.0000000
See ?which for more information.
HTH,
Marc Schwartz
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