Hi,

Try,

apply(a,1,which.max)

[1] 3 1 3

A.K.

----- Original Message -----

From: Christopher Desjardins <

cddesjardins@gmail.com>

To: r-help at r-project.org

Cc:

Sent: Tuesday, July 17, 2012 6:03 PM

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

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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