[R] Group by multiple variables

[Sebastian P. Luque]

On Mon, 30 May 2011 16:47:45 -0500,
"Mendolia, Franco" <fmendolia at mcw.edu> wrote:

> Hello, I would like to create a group variable that is based on the
> values of three variables:

> For example,

>> dat <- data.frame(A=c(1,1,1,1,1,2,2,2,2,2),
>                     B=c(1,1,1,5,5,5,9,9,9,9),
> C=c(1,1,1,1,1,2,2,7,7,7))
>> dat
>    A B C 1 1 1 1 2 1 1 1 3 1 1 1 4 1 5 1 5 1 5 1 6 2 5 2 7 2 9 2 8 2 9
> 7 9 2 9 7 10 2 9 7

[...]

One option:

dat <- within(dat, {grp <- factor(paste(A, B, C))})


-- 
Seb