Finding row index containing maximum value using R

Question

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]         


        

Answer 1

See ?order. You just need the last index (or first, in decreasing order), so this should do the trick:

order(matrix[,2],decreasing=T)[1]