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

[arun]

Hi,
Try,
apply(a,1,which.max)
[1] 3 1 3

A.K.



----- Original Message -----
From: Christopher Desjardins <cddesjardins at 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]]

______________________________________________
R-help at r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.