On Mon, 30 May 2011 16:47:45 -0500,
"Mendolia, Franco" <fmendo...@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
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