And another way is to remember properties of matrix multiplication: y %*% diag(x)
On Fri, Apr 20, 2012 at 8:35 AM, David Winsemius <dwinsem...@comcast.net> wrote: > > On Apr 20, 2012, at 4:57 AM, Dimitris Rizopoulos wrote: > >> try this: >> >> x <- 1:3 >> y <- matrix(1:12, ncol = 3, nrow = 4) >> >> y * rep(x, each = nrow(y)) > > > Another way with a function specifically designed for that purpose: > > sweep(y, 2, x, "*") > > -- David. > > >> >> >> I hope it helps. >> >> Best, >> Dimitris >> >> >> On 4/20/2012 10:51 AM, Vincy Pyne wrote: >>> >>> Dear R helpers >>> >>> Suppose >>> >>> x<- c(1:3) >>> >>> y<- matrix(1:12, ncol = 3, nrow = 4) >>> >>>> y >>> >>> [,1] [,2] [,3] >>> [1,] 1 5 9 >>> [2,] 2 6 10 >>> [3,] 3 7 11 >>> [4,] 4 8 12 >>> >>> I wish to multiply 1st column of y by first element of x i.e. 1, 2nd >>> column of y by 2nd element of x i.e. 2 an so on. Thus the resultant matrix >>> should be like >>> >>>> z >>> >>> >>> [,1] [,2] [,3] >>> >>> [1,] 1 10 27 >>> >>> [2,] 2 12 30 >>> >>> [3,] 3 14 33 >>> >>> [4,] 4 16 36 >>> >>> >>> When I tried simple multiplication like x*y, y is getting multiplied >>> column-wise >>> >>>> x*z >>> >>> [,1] [,2] [,3] >>> [1,] 1 5 9 >>> [2,] 4 12 20 >>> [3,] 9 21 33 >>> [4,] 16 32 48 >>> >>> >>> Kindly guide >>> >>> Regards >>> >>> Vincy >>> >>> [[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. >> >> >> -- >> Dimitris Rizopoulos >> Assistant Professor >> Department of Biostatistics >> Erasmus University Medical Center >> >> Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands >> Tel: +31/(0)10/7043478 >> Fax: +31/(0)10/7043014 >> Web: http://www.erasmusmc.nl/biostatistiek/ >> >> ______________________________________________ >> 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. > > > David Winsemius, MD > West Hartford, CT > > > ______________________________________________ > 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. -- Gregory (Greg) L. Snow Ph.D. 538...@gmail.com ______________________________________________ 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.
