[R] Using apply

Peter Langfelder peter@|@ng|e|der @end|ng |rom gm@||@com
Wed Oct 31 04:44:08 CET 2018

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.


On Tue, Oct 30, 2018 at 7:28 PM Steven Yen <styen using 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 using 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.

More information about the R-help mailing list