It should be said that for many basic statistics, there are faster functions than apply, for example here you want
sum = colSums(x) As already said, for sum of squares you would do colSums(x^2). Many useful functions of this kind are implemented in package matrixStats. Once you install it, either look at the package manual or type ls("package:matrixStats") to see a list of functions. Most if not all have self-explanatory names. HTH, Peter On Tue, Oct 30, 2018 at 7:28 PM Steven Yen <st...@ntu.edu.tw> wrote: > > I need help with "apply". Below, I have no problem getting the column sums. > 1. How do I get the sum of squares? > 2. In general, where do I look up these functions? > Thanks. > > x<-matrix(1:10,nrow=5); x > sum <- apply(x,2,sum); sum > > > > > [[alternative HTML version deleted]] > > ______________________________________________ > 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.