On Tue, 31 Aug 2004, Liaw, Andy wrote: > If you insist, here's one way: > > my.blockwisesum <- function(x, n, ...) { > tapply(x, seq(1, length(x), by=n), sum, ...) > }
If x is large, rowsum() should be faster than tapply(). -thomas > > Andy > > > From: Lutz Prechelt > > > > I am looking for a function like > > my.blockwisesum(vector, n) > > that computes sums of disjoint subsequences of length n from vector > > and can work with vector lengths that are not a multiple of n. > > > > It should give me for instance > > my.blockwisesum(1:10, 3) == c(6, 15, 24, 10) > > > > Is there a builtin function that can do this? > > One could do it by coercing the vector into a matrix of width n, > > and then use apply, > > but that is cumbersome if the length is not divisible by n, > > is it not? > > Any other ideas? > > > > Lutz > > > > Prof. Dr. Lutz Prechelt; [EMAIL PROTECTED] > > Institut fuer Informatik; Freie Universitaet Berlin > > Takustr. 9; 14195 Berlin; Germany > > +49 30 838 75115; http://www.inf.fu-berlin.de/inst/ag-se/ > > > > ______________________________________________ > > [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 > > > > > > ______________________________________________ > [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 > Thomas Lumley Assoc. Professor, Biostatistics [EMAIL PROTECTED] University of Washington, Seattle ______________________________________________ [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