[R] Sort matrix by column 1 ascending then by column 2 decending

[Paul Geeleher]

Nice. Works perfectly.

On Wed, May 27, 2009 at 2:03 PM, Henrique Dallazuanna <wwwhsd at gmail.com> wrote:
> 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 at 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
>>
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>> and provide commented, minimal, self-contained, reproducible code.
>
>
>
> --
> Henrique Dallazuanna
> Curitiba-Paraná-Brasil
> 25° 25' 40" S 49° 16' 22" O
>



-- 
Paul Geeleher
School of Mathematics, Statistics and Applied Mathematics
National University of Ireland
Galway
Ireland