>-----Original Message-----
>From: [EMAIL PROTECTED]
>[mailto:[EMAIL PROTECTED] On Behalf Of John Janmaat
>Sent: Wednesday, April 02, 2003 12:39 PM
>To: [EMAIL PROTECTED]
>Subject: [R] Index of item in matrix
>
>
>Hello All,
>
>Is there a fast way to find the index(row and column) of a point in a
>matrix?
>
>Thanks,
>
>John.
Look at ?which.
Specifically the form: which(x, arr.ind = TRUE)
> m <- matrix(1:12,3,4)
> m
[,1] [,2] [,3] [,4]
[1,] 1 4 7 10
[2,] 2 5 8 11
[3,] 3 6 9 12
> which(m == 9, arr.ind = TRUE)
row col
[1,] 3 3
> m[3,3]
[1] 9
HTH,
Marc Schwartz
______________________________________________
[EMAIL PROTECTED] mailing list
https://www.stat.math.ethz.ch/mailman/listinfo/r-help
