library(Matrix) result <- newX %*% Diagonal( unlist(beta) ) Is beta really a list, or is it a vector? The str function can help with this... in most cases it is a numeric mode vector and the unlist is not needed. --------------------------------------------------------------------------- Jeff Newmiller The ..... ..... Go Live... DCN:<[email protected]> Basics: ##.#. ##.#. Live Go... Live: OO#.. Dead: OO#.. Playing Research Engineer (Solar/Batteries O.O#. #.O#. with /Software/Embedded Controllers) .OO#. .OO#. rocks...1k --------------------------------------------------------------------------- Sent from my phone. Please excuse my brevity.
On September 29, 2014 5:03:30 PM PDT, Yara Abu Awad <[email protected]> wrote: >Hi, > >I'm trying to use a function to multiply a matrix (newX) with a simple >list (beta). >I know that I can simply use matrix multiplication i.e. newX >%*%as.matrix(beta) >and this works fine. However, the matrix multiplication gives me the >sum of each row. What I really need are the new values of all the >columns in newX if they were multiplied by beta (so the first column of >newX should be multiplied by the first value in beta, second column by >the second value etc..) > >This is the function I'm trying to use: > >Terms <-NULL >count <- 0 > >for (i in 1: ncol(newX)){ > for (j in 1: length(beta)){ > Terms <- cbind (Terms,(newX[,i]*beta[j])) > } >} > >I don't get an error message, however the function runs for a long time >(about an hour) without resolving and I end up stopping it. > > > >Now, if I multiply every individual column by each value of beta, the >calculation works (code is below): >newX[,1]*beta[1] >newX[,2]*beta[2] > >but since newX has 520 columns and beta has 520 values, I'd rather use >a shortcut!! > > >I can't figure out why the above function doesn't work. I've used it to >multiply two matrices and it works just fine. >Any insight would be appreciated. > >Yara > >______________________________________________ >[email protected] 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. ______________________________________________ [email protected] 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.
