# [R] R matrix sorting question

Tuszynski, Jaroslaw W. JAROSLAW.W.TUSZYNSKI at saic.com
Thu May 19 20:30:05 CEST 2005

```Try:

> A=matrix(c(1,3,4,5,7, -0.2, 0.8, 0.3, 0.2, 0.9 ),5,2)
> A
[,1] [,2]
[1,]    1 -0.2
[2,]    3  0.8
[3,]    4  0.3
[4,]    5  0.2
[5,]    7  0.9
> A[order(A[,2]), ]
[,1] [,2]
[1,]    1 -0.2
[2,]    5  0.2
[3,]    4  0.3
[4,]    3  0.8
[5,]    7  0.9

Jarek
====================================================\=======

Jarek Tuszynski, PhD.                           o / \
Science Applications International Corporation  <\__,|
(703) 676-4192                                   ">   \
Jaroslaw.W.Tuszynski at saic.com                     `    \

-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of
insu_paek at harcourt.com
Sent: Thursday, May 19, 2005 1:43 PM
To: R-help at stat.math.ethz.ch
Subject: [R] R matrix sorting question

Dear there,

I am trying to do the following stuff. Could you let me know how to do
it efficiently?

> aaa
[,1] [,2]
[1,]    1 -0.2
[2,]    3  0.8
[3,]    4  0.3
[4,]    5  0.2
[5,]    7  0.9

And I would like to sort the matrix by column 2 (and accordingly  column 1
sorted as well).
The desired matrix will be

1  -0.2
5   0.2
4   0.3
3   0.8
7   0.9

If using Excel or SAS, I can do this easily, but I couldn't figure out how
to do it in R.
Could you let me know the efficient way to do this ?
I appreciate if the solution or reply comes as quickly as possible.

Thank you very much.

Insu

______________________________________________
R-help at stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help