Find row and column index of maximum value in a matrix [duplicate]

Question

I wish to find the maximum element-value of a matrix and it's location (in row and column id in the matrix).

I am using the following function to return the row and column of the matrix.

This seems like a bad hack -- it's the sort of thing where i'm probably missing a native method. Is there a better / more R way?

Here's my function:

matxMax <- function(mtx) {     colmn <- which(mtx == max(mtx)) %/% nrow(mtx) + 1     row <- which(mtx == max(mtx)) %% nrow(mtx)     return( matrix(c(row, colmn), 1)) } 

I use is as follows:

mm <- matrix(rnorm(100), 10, 10) maxCords <- matxMax(mm) mm[maxCords] 

Answer 1

You could do

## Some data set.seed(123) mm <- matrix(rbinom(40, 20, 0.5), 8, 5) mm #      [,1] [,2] [,3] [,4] [,5] # [1,]    9   10    8   11   11 # [2,]   12   10    6   11   12 # [3,]    9   14    9   10    6 # [4,]   13   10   14   11   10 # [5,]   13   11   13    9   12 # [6,]    6   10   11    8    8 # [7,]   10    7   11   14    9 # [8,]   13   13   16   13    8  which(mm == max(mm), arr.ind = TRUE) #      row col # [1,]   8   3