Index of item in matrix
Sundar's solution is better than mine unless the code must also work in S-Plus. Spencer Graves
Sundar Dorai-Raj wrote:
Or more simply:
> set.seed(1) > A <- array(rnorm(12), dim=c(3,4)) > which(round(A) == 1, arr.ind = TRUE)
row col [1,] 2 2 [2,] 1 4 Though, the original post may need more clarification. Sundar Spencer Graves wrote:
Satisfying what conditions? Does the following example help you get what you want?
> set.seed(1) > A <- array(rnorm(12), dim=c(3,4)) > > sel <- (round(A)==1) > sel
[,1] [,2] [,3] [,4] [1,] FALSE FALSE FALSE TRUE [2,] FALSE TRUE FALSE FALSE [3,] FALSE FALSE FALSE FALSE
> cbind(row(A)[sel],col(A)[sel])
[,1] [,2] [1,] 2 2 [2,] 1 4 Spencer Graves John Janmaat wrote:
Hello All, Is there a fast way to find the index(row and column) of a point in a matrix? Thanks, John.
______________________________________________ R-help at stat.math.ethz.ch mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help