Try this:
> key <- rownames(a)
> key[key == "AT"] <- "TA"
> do.call(rbind, by(a, key, colSums))
V2 V3 V4 V5
AA 1 5 9 13
TA 5 13 21 29
TT 4 8 12 16
On Mon, May 11, 2009 at 4:53 PM, Crosby, Jacy R
<jacy.r.cro...@uth.tmc.edu>wrote:
> I'm working with genotype data in a frequency table:
>
> > a=matrix(1:16, nrow=4)
> > rownames(a)=c("AA","AT","TA","TT")
> > a
> [,1] [,2] [,3] [,4]
> AA 1 5 9 13
> AT 2 6 10 14
> TA 3 7 11 15
> TT 4 8 12 16
>
> 'AT' and 'TA' are essentially the same, and I'd like to combine (add) the
> rows to reflect this. The final matrix should be:
>
> [,1] [,2] [,3] [,4]
> AA 1 5 9 13
> AT 5 13 21 29
> TT 4 8 12 16
>
> Is there a fast way to do this?
>
> Thanks in advance!
>
> Jacy Crosby
> jacy.r.cro...@uth.tmc.edu
>
>
> [[alternative HTML version deleted]]
>
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> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html<http://www.r-project.org/posting-guide.html>
> and provide commented, minimal, self-contained, reproducible code.
>
--
Jim Holtman
Cincinnati, OH
+1 513 646 9390
What is the problem that you are trying to solve?
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