Given the following matrix lets assume I want to find the maximum value in column two:

mat <- matrix(c(1:3,7:9,4:6), byrow = T, nc = 3)

mat

[,1] [,2] [,3]

[1,] 1 2 3

[2,] 7 8 9

[3,] 4 5 6

I know max(mat[,2]) will return 8. How can I return the row index, in this case, row two?