Thanks, Henrique. The second option you suggested is about twice as fast as my original application.
Much appreciated, Kevin On Jan 5, 2011, at 6:30 PM, Henrique Dallazuanna wrote: > Try this: > > apply(apply(m, 2, rep, each = 2), 1, rep, each = 2) > > or > > m[rep(seq(nrow(m)), each = 2), rep(seq(ncol(m)), each = 2)] > > On Wed, Jan 5, 2011 at 10:03 AM, Kevin Ummel <kevinum...@gmail.com> wrote: > Hi everyone, > > I'm looking for a way to 'explode' a matrix like this: > > > matrix(1:4,2,2) > [,1] [,2] > [1,] 1 3 > [2,] 2 4 > > into a matrix like this: > > > matrix(c(1,1,2,2,1,1,2,2,3,3,4,4,3,3,4,4),4,4) > [,1] [,2] [,3] [,4] > [1,] 1 1 3 3 > [2,] 1 1 3 3 > [3,] 2 2 4 4 > [4,] 2 2 4 4 > > My current kludge is this: > > v1=rep(1:4,each=2,times=2) > v2=v1[order(rep(1:2,each=4,times=2))] > matrix(v2,4,4) > > But I'm hoping there's a more efficient solution that I'm not aware of. > > Many thanks, > Kevin > > ______________________________________________ > 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. > > > > -- > Henrique Dallazuanna > Curitiba-Paraná-Brasil > 25° 25' 40" S 49° 16' 22" O [[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.
