or this x[,!(colSums(abs(x)) == 0)]
On Jan 15, 10:00 am, Marc Schwartz <wdwgol...@gmail.com> wrote: > Careful: > > x <- matrix(c(1, 5, 3, 2, 1, 4, -1, 0, 1), > ncol = 3, nrow = 3) > > > x > > [,1] [,2] [,3] > [1,] 1 2 -1 > [2,] 5 1 0 > [3,] 3 4 1 > > > x[, colSums(x) != 0] > > [,1] [,2] > [1,] 1 2 > [2,] 5 1 > [3,] 3 4 > > Not quite the result wanted... :-) > > Try this: > > > x[, colSums(x == 0) != nrow(x)] > > [,1] [,2] > [1,] 1 2 > [2,] 5 1 > [3,] 3 4 > > x <- matrix(c(1, 5, 3, 2, 1, 4, -1, 0, 1), > ncol = 3, nrow = 3) > > > x[, colSums(x == 0) != nrow(x)] > > [,1] [,2] [,3] > [1,] 1 2 -1 > [2,] 5 1 0 > [3,] 3 4 1 > > HTH, > > Marc Schwartz > > on 01/14/2009 04:29 PM Gustavo Carvalho wrote: > > > > > Sorry for the double post, but this is probably faster: > > > x[, colSums(x) != 0] > > > On Wed, Jan 14, 2009 at 8:22 PM, Gustavo Carvalho > > <gustavo.bi...@gmail.com> wrote: > >> You can also try this: > > >> x[,-(which(colSums(x) == 0))] > > >> Cheers, > > >> Gustavo. > > >> On Wed, Jan 14, 2009 at 8:01 PM, Anthony Dick <ad...@uchicago.edu> wrote: > >>> Hello- > > >>> I would like to remove the columns of a matrix that contain all zeros. For > >>> example, from > >>> x<-matrix(c(1,5,3,2,1,4,0,0,0), ncol=3,nrow=3) > > >>> I would like to remove the third column. However, because this is in a > >>> loop > >>> I need a way to first determine which columns are all zeros, and only then > >>> remove them. I.e., I don't know which column of x contains all zeros until > >>> after x is created. > > >>> Thanks! > > >>> Anthony > > ______________________________________________ > r-h...@r-project.org mailing listhttps://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guidehttp://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. ______________________________________________ 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.
