[R] Sorting a matrix

Bert Gunter
Thu, 10 Jul 2008 18:40:45 -0000

1. This is a data frame, not a matrix ! -- ?data.frame

2. help.search("sort") is the first thing you should have done. You
probably
wouldn't have needed to post if you had.

3. The canonical answer is ?order and indexing  -- as in:

yourdf[order(yourdf$Age),]

Note that order() can be used to sort by more than one column -- e.g. Sex
and then Age within Sex.

4. The orderBy() function in the doBy package -- and probably there are
others -- can do this exactly.

Cheers,

Bert Gunter
Genentech, Inc.

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On
Behalf Of Angelo Scozzarella
Sent: Thursday, July 10, 2008 11:21 AM
To: r-help at r-project.org
Subject: [R] Sorting a matrix

Hi,

I want to sort a matrix by a specific variable without changing the
row binding between variables.

Ex.

Name	Sex		Age
Fred	M		24
John	M		18
Mary	F		21


ordered by Age


Name	Sex		Age
John	M		18
Mary	F		21
Fred	M		24



Thanks



Angelo

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