I love R for it: if you experiment enough with t() you can find a way to multiply almost anything by almost anything! :)
On Thu, Nov 3, 2016 at 5:32 PM, Rui Barradas <ruipbarra...@sapo.pt> wrote: > Hello, > > Take advantage that in R '*' recycles its arguments (the shorter one) and > that the operation is performed column-wise: > > t(y * t(x)) > > Hope this helps, > > Rui Barradas > > > Em 03-11-2016 21:05, Dimitri Liakhovitski escreveu: >> >> Hello! >> >> I have a matrix x and a vector y: >> >> x <- matrix(1:6, ncol = 2) >> y <- c(2,3) >> >> I need to multiply the first column of x by 2 (y[1]) and the second >> column of x by 3 (y[2]). >> >> Of course, I could do this - but it's column by column: >> >> x[,1] <- x[,1] * y[1] >> x[,2] <- x[,2] * y[2] >> x >> >> Or I could repeat each element of y and multiply two matrices - that's >> better: >> >> rep.row<-function(x,n){ >> matrix(rep(x,each=n),nrow=n) >> } >> y <- rep.row(y, nrow(x)) >> x * y >> >> However, maybe there is a more elegant r-like way of doing it? >> Thank you! >> > -- Dimitri Liakhovitski ______________________________________________ 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.