Find row and column index of maximum value in a matrix
matrix, r
Solution
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
Problem
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] ```