Try this, a[ ,as.logical(colSums(a))]
mind an unfortunate logical vs integer indexing trap: isTRUE(all.equal( a[ ,!!colSums(a)] , a[ ,colSums(a)] )) [1] FALSE HTH, baptiste 2009/8/18 Alberto Lora M <albertolo...@gmail.com>: > Hi Everbody > > Could somebody help me.? > > I need to remove the columns where the sum of it components is equal to > zero. > > For example > >> a<-matrix(c(0,0,0,0,0,0,0,1,0,1,0,0,0,0,0,0,0,0,1,1,0,0,1,0), ncol=4) >> a > [,1] [,2] [,3] [,4] > [1,] 0 0 0 1 > [2,] 0 1 0 1 > [3,] 0 0 0 0 > [4,] 0 1 0 0 > [5,] 0 0 0 1 > [6,] 0 0 0 0 > > Columns 1 and 3 should be removed > > the result should be the dollowing matrix > > [,2] [,4] > [1,] 0 1 > [2,] 1 1 > [3,] 0 0 > [4,] 1 0 > [5,] 0 1 > [6,] 0 0 > > Thanks again > > > -- > Alberto Lora Michiels > Rue du Progrès, 6B > 7860 Lessines > GSM 32(0)496659457 > > [[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. > > -- _____________________________ Baptiste Auguié School of Physics University of Exeter Stocker Road, Exeter, Devon, EX4 4QL, UK http://newton.ex.ac.uk/research/emag ______________________________________________ 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.
