[R] How to sort the elements in a matrix?

[Steve Lianoglou]

Hi,

On Sep 22, 2009, at 1:20 PM, FMH wrote:

> Dear All,
>
> Let ab is the combination of matrices a and b.
>
>
> a <- matrix(c(1,2,3,4), nrow = 2, ncol = 2)
> b <- matrix(c(4,3,1,2), nrow = 2, ncol = 2)
> ab <- rbind(a, b)
>
>> From matrix ab, could someone give some advice on the way to sort  
>> all elements in column 2, by the sequence of the elements in column  
>> 1 in ascending order?

R> ab[order(ab[,1]),2]
[1] 3 4 2 1

-steve

--
Steve Lianoglou
Graduate Student: Computational Systems Biology
   |  Memorial Sloan-Kettering Cancer Center
   |  Weill Medical College of Cornell University
Contact Info: http://cbio.mskcc.org/~lianos/contact