[BioC] How to sort a matrix based on its column names and preserving the identical column names

[Oleg Sklyar]

mat[, order(colnames(mat))]

order provides indexes of sorted elements without affecting their names.
Sort works in your case half ways only because you are sorting
characters, and columns can be identified by characters, otherwise it is
wrong.

Here is the working example:

> x<-c("col","abc","def","abc","col")
> a<-matrix(runif(25),ncol=5,nrow=5)
> colnames(a) <- x
> a
           col        abc       def        abc       col
[1,] 0.9815985 0.65855865 0.9982046 0.07781167 0.3228944
[2,] 0.5970836 0.19195563 0.9082061 0.80489513 0.9190933
[3,] 0.8147790 0.13499074 0.9431437 0.41154237 0.6487952
[4,] 0.7661668 0.26216671 0.6694043 0.66462428 0.2177653
[5,] 0.5604505 0.04371932 0.7873665 0.44849293 0.1700327
> a[,order(x)]
            abc        abc       col       col       def
[1,] 0.65855865 0.07781167 0.9815985 0.3228944 0.9982046
[2,] 0.19195563 0.80489513 0.5970836 0.9190933 0.9082061
[3,] 0.13499074 0.41154237 0.8147790 0.6487952 0.9431437
[4,] 0.26216671 0.66462428 0.7661668 0.2177653 0.6694043
[5,] 0.04371932 0.44849293 0.5604505 0.1700327 0.7873665

> order(x)
[1] 2 4 1 5 3

On Fri, 2007-08-03 at 05:36 -0700, carol white wrote:
> Hello,
> How to sort a matrix based on its column names and preserving the identical column names.
> 
> when I use mat [, sort(colnames(mat))], sort changes all column names to unique ones. for ex,  if the name of 2 columns is col, the 2nd will be changed to col.1 whereas I want to keep the col name for the two columns
> 
> col    col -> col   col.1
> 
> thanks
> 
>        
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-- 
Dr. Oleg Sklyar * EBI-EMBL, Cambridge CB10 1SD, England * +44-1223-494466