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] [,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?

1
117
11/25/2016 8:22:45 PM

See ?which.max

> which.max( matrix[,2] )
[1] 2
164
4/13/2009 11:44:58 AM

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