Try this:

cbind(sort(x[,1]), unlist(tapply(x[,2], x[,1], sort, decreasing = T)))

On Wed, May 27, 2009 at 9:39 AM, Paul Geeleher <paulgeeleher@gmail.com>wrote:

> I've got a matrix with 2 columns and n rows. I need to sort it first
> by the values in column 1 ascending. Then for values which are the
> same in column 1, sort by column 2 decending. For example:
>
> 2 .5
> 1 .3
> 1 .5
> 3 .2
>
> Goes to:
>
> 1 .5
> 1 .3
> 2 .5
> 3 .2
>
> This is easy to do in spreadsheet programs but I can't seem to work
> out how to do it in R and haven't been able to find a solution
> anywhere.
>
>
> Thanks!
>
> -Paul.
>
> --
> Paul Geeleher
> School of Mathematics, Statistics and Applied Mathematics
> National University of Ireland
> Galway
> Ireland
>
> ______________________________________________
> R-help@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.
>



-- 
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O

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