Re: [R] [PS] Switching entries in vector in by groups of two

From: Ben Fairbank <BEN_at_ssanet.com>
Date: Fri, 27 Jun 2008 09:35:03 -0500

Perhaps

xnew <- x[1:length(x)+c(1,-1)]

will do it.

Ben Fairbank

-----Original Message-----
From: r-help-bounces_at_r-project.org [mailto:r-help-bounces_at_r-project.org] On Behalf Of David Afshartous
Sent: Friday, June 27, 2008 9:11 AM
To: r-help_at_r-project.org
Subject: [PS] [R] Switching entries in vector in by groups of two

All,

I have a long vector that contains an even number of entries. I'd like to
switch the 1st and 2nd entry, the 3rd and 4th, and so on, without writing a
loop.

This code works:

X = c(8, 10, 6, 3, 20, 1)
index = c(2,1,4,3,6,5)
X[index]

But for a long list is there a way to generate the index? I can get the parts to the index as:

index.odd = seq(1,length(X), by = 2)
index.even = index.odd + 1

Is there a simple way to interweave them to produce the desired index? Or
is there a better way?

Cheers,
David



R-help_at_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.

R-help_at_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. Received on Fri 27 Jun 2008 - 14:45:10 GMT

Archive maintained by Robert King, hosted by the discipline of statistics at the University of Newcastle, Australia.
Archive generated by hypermail 2.2.0, at Fri 27 Jun 2008 - 15:01:14 GMT.

Mailing list information is available at https://stat.ethz.ch/mailman/listinfo/r-help. Please read the posting guide before posting to the list.

list of date sections of archive