Hi, See ?sweep
For instance, to get your matrix two: > sweep(a, 2, b, "/") [,1] [,2] [1,] 2 24 [2,] 4 28 [3,] 6 32 [4,] 8 36 [5,] 10 40 Sarah On Mon, Jul 27, 2015 at 4:04 PM, Steven Yen <sye...@gmail.com> wrote: > I need help with element-by-element division. Below, matrices a and c are > both 5 x 2 and element-by-element division works as (I) expected. What if > matrix is 1 by 2: to divide first column of a by b[1] and second column of > a by b[2]. I had to go around (two ways) to make it work. In Gauss, these > can be dine by a./b and a./c. Any such simple way in R? Thank! > >> a<-matrix(1:10,nrow=5); a > [,1] [,2] > [1,] 1 6 > [2,] 2 7 > [3,] 3 8 > [4,] 4 9 > [5,] 5 10 >> b<-matrix(c(0.5,0.25),nrow=1); b > [,1] [,2] > [1,] 0.5 0.25 >> c<-matrix(rep(c(0.5,0.25),5),nrow=5,byrow=T); c > [,1] [,2] > [1,] 0.5 0.25 > [2,] 0.5 0.25 > [3,] 0.5 0.25 > [4,] 0.5 0.25 > [5,] 0.5 0.25 > >> one<-a/c; one [,1] [,2] > [1,] 2 24 > [2,] 4 28 > [3,] 6 32 > [4,] 8 36 > [5,] 10 40 > > >> two<-a/b > Error in a/b : non-conformable arrays >> two<-cbind(a[,1]/b[1],a[,2]/b[2]); two > [,1] [,2] > [1,] 2 24 > [2,] 4 28 > [3,] 6 32 > [4,] 8 36 > [5,] 10 40 > >> b2<-matrix(rep(b,5),nrow=5,byrow=T); b2 [,1] [,2] > [1,] 0.5 0.25 > [2,] 0.5 0.25 > [3,] 0.5 0.25 > [4,] 0.5 0.25 > [5,] 0.5 0.25> a/b2 [,1] [,2] > [1,] 2 24 > [2,] 4 28 > [3,] 6 32 > [4,] 8 36 > [5,] 10 40 -- Sarah Goslee http://www.functionaldiversity.org ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.