[R] How to 'explode' a matrix
Hi everyone, I'm looking for a way to 'explode' a matrix like this: matrix(1:4,2,2) [,1] [,2] [1,]13 [2,]24 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,]1133 [2,]1133 [3,]2244 [4,]2244 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.
Re: [R] How to 'explode' a matrix
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,]13 [2,]24 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,]1133 [2,]1133 [3,]2244 [4,]2244 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.
Re: [R] How to 'explode' a matrix
Kevin Ummel kevinummel at gmail.com writes: I'm looking for a way to 'explode' a matrix like this: matrix(1:4,2,2) [,1] [,2] [1,]13 [2,]24 This is the Kronecker product of your matrix with the matrix (1 1 ; 1 1) m - matrix(1:4,2,2) kronecker(m,matrix(1,2,2)) cheers Ben Bolker __ 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.
Re: [R] How to 'explode' a matrix
Hi Kevin, Take a look at ?kronecker HTH, Jorge On Wed, Jan 5, 2011 at 7:03 AM, Kevin Ummel wrote: Hi everyone, I'm looking for a way to 'explode' a matrix like this: matrix(1:4,2,2) [,1] [,2] [1,]13 [2,]24 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,]1133 [2,]1133 [3,]2244 [4,]2244 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. [[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.
Re: [R] How to 'explode' a matrix
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,]13 [2,]24 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,]1133 [2,]1133 [3,]2244 [4,]2244 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.
