Thanks David & Bert. It turned out that what I actually wanted was much simpler. my vector's elements are 0&1 and the right way to "summarize" it is hist(which(v==1)) however, your replies were quire educational! Thanks again, Sam.
> * Bert Gunter <thagre.ore...@trar.pbz> [2012-08-10 12:57:40 -0700]: > >> sz <- function(x,k)tapply(x,(seq_along(x)-1)%/%k, sum) > > On Fri, Aug 10, 2012 at 12:37 PM, David Winsemius > <dwinsem...@comcast.net> wrote: >> >> On Aug 10, 2012, at 12:20 PM, Sam Steingold wrote: >> >>> I have a long numeric vector v (length N) and I want create a shorter >>> vector of length N/k consisting of sums of k-subsequences of v: >>> >>> v <- c(1,2,3,4,5,6,7,8,9,10) >>> >>> N=10, k=3 >>> ===> [6,15,24,10] >> >>> w <- tapply( v ,rep(1:(N/k +1), each=k, len=N ) , sum) -- Sam Steingold (http://sds.podval.org/) on Ubuntu 12.04 (precise) X 11.0.11103000 http://www.childpsy.net/ http://camera.org http://iris.org.il http://palestinefacts.org http://dhimmi.com http://truepeace.org At war time "salt of the earth" becomes "cannon fodder". ______________________________________________ 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.
