You can create a suitable matrix bb as below (note the byrow = TRUE argument)
aa<-matrix(1:30,nrow=10,ncol=3); aa bb<-matrix(c(100,100,1),nrow=10,ncol=3, byrow = TRUE); bb dim(aa) dim(bb) aa * bb You can also use matrix multiplication, but that;s slightly more involved: aa<-matrix(1:30,nrow=10,ncol=3); aa bb<-matrix(0,nrow=3,ncol=3); diag(bb) = c(100,100,1); bb dim(aa) dim(bb) aa %*% bb HTH, Peter On Wed, Jan 7, 2015 at 3:05 PM, Steven Yen <sye...@gmail.com> wrote: > I like to multiple the first and second column of a 10 x 3 matrix by 100. > The following did not work. I need this in an operation with a much larger > scale. Any help? > > aa<-matrix(1:30,nrow=10,ncol=3); aa > bb<-matrix(c(100,100,1),nrow=1,ncol=3); bb > dim(aa) > dim(bb) > aa*bb > > Results: > >> aa<-matrix(1:30,nrow=10,ncol=3); aa > [,1] [,2] [,3] > [1,] 1 11 21 > [2,] 2 12 22 > [3,] 3 13 23 > [4,] 4 14 24 > [5,] 5 15 25 > [6,] 6 16 26 > [7,] 7 17 27 > [8,] 8 18 28 > [9,] 9 19 29 > [10,] 10 20 30 >> bb<-matrix(c(100,100,1),nrow=1,ncol=3); bb > [,1] [,2] [,3] > [1,] 100 100 1 >> dim(aa) > [1] 10 3 >> dim(bb) > [1] 1 3 >> aa*bb > Error in aa * bb : non-conformable arrays > >> > > ______________________________________________ > 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. ______________________________________________ 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.