as.matrix(df) %*% vec Michael
On Mar 7, 2012, at 3:14 PM, Alexander Shenkin <ashen...@ufl.edu> wrote: > Hello, > > I need to take a dot product of each row of a dataframe and a vector. > The number of columns will be dynamic. The way I've been doing it so > far is contorted. Is there a better way? > > dotproduct <- function(dataf, v2) { > apply(t(t(as.matrix(a)) * v2),1,sum) #contorted! > } > > df = data.frame(a=c(1,2,3),b=c(4,5,6)) > vec = c(4,5) > dotproduct(df, vec) > > > thanks, > allie > > ______________________________________________ > 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. ______________________________________________ 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.