I still remember my public spanking from Ben Bolker on the unnecessary
use of "which" in this instance.
> MM <- matrix(c(1:10,sample(-10:10,10)),nrow=10)
> MM
[,1] [,2]
[1,] 1 -1
[2,] 2 5
[3,] 3 -2
[4,] 4 -3
[5,] 5 0
[6,] 6 7
[7,] 7 -9
[8,] 8 1
[9,] 9 6
[10,] 10 4
> MM[MM[,2]<0, ]
[,1] [,2]
[1,] 1 -1
[2,] 3 -2
[3,] 4 -3
[4,] 7 -9
> MM[MM[,2]>0, ]
[,1] [,2]
[1,] 2 5
[2,] 6 7
[3,] 8 1
[4,] 9 6
[5,] 10 4
--
David Winsemius
On Feb 9, 2009, at 9:46 AM, Ian Fiske wrote:
If your matrix is called mat, how about
mat[which(mat[,2] > 0), ]
mat[which(mat[,2] < 0), ]
-Ian
mentor_ wrote:
Hi,
I have a matrix with negative and positiv values.
How can I get either the negative or positive values from the matrix?
Matrix:
[,1] [,2]
[1,] 1 -3
[2,] 2 -2
[3,] 3 5
[4,] 4 -2
[5,] 5 9
[6,] 6 8
[7,] 7 -2
What I want to have is:
[,1] [,2]
[1,] 1 -3
[2,] 2 -2
[3,] 4 -2
[4,] 7 -2
and:
[,1] [,2]
[1,] 3 5
[2,] 5 9
[3,] 6 8
Regards
--
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