Thanks Henrique, Marc, and Gabor!
On 6/27/08 10:17 AM, "Henrique Dallazuanna" <[EMAIL PROTECTED]> wrote: > Try this: > > ave(X, rep(1:(length(X)/2), each = 2), FUN=rev) > > On Fri, Jun 27, 2008 at 11:11 AM, David Afshartous <[EMAIL PROTECTED]> > wrote: >> >> 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@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. > > [[alternative HTML version deleted]] ______________________________________________ R-help@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.
