[R] Finding the column with the maximum value by row

[R. Michael Weylandt]

apply(a, 1, which.max)

Apply the which.max() function to the matrix a row-wise (1)

Michael

On Tue, Jul 17, 2012 at 5:03 PM, Christopher Desjardins
<cddesjardins at gmail.com> wrote:
> Hi,
> Let's say I have the following data:
>
>> a=matrix(c(1,2,4,4,2,1,1,2,4),nrow=3,byrow=T)
>
>> a
>
>      [,1] [,2] [,3]
>
> [1,]    1    2    4
>
> [2,]    4    2    1
>
> [3,]    1    2    4
>
> What syntax should I use to get R to tell me the column that corresponds to
> the maximum value for each row?
>
> For my example, I would like to get a vector that says 3, 1, 3 because the
> maximum value for row 1 is in column 3, the maximum value for row 2 is in
> column 1, and the maximum value for row 3 is in column 3.
>
> Does that make sense?
>
> Please cc me if you reply!
>
> Chris
>
>         [[alternative HTML version deleted]]
>
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