Hi [EMAIL PROTECTED] napsal dne 03.09.2008 16:39:07:
> Dear list, > I'm wondering how to optimize functions/processes like the one shown > below (which simplifies something we're trying to do with very large > datasets). > In many cases I've noticed that using apply, sapply etc can help > speeding up processes, but in this case I don't see how I could do so. > > a <- runif(10000000,0.5,1.6) > C <- 2 > M <- 10000000 > system.time( for (i in 1:(M-1)) {C <- C* c(a[i],a[i+1])} ) Maybe simple math? You want last two members of 2*cumprod(a). So > system.time(2*cumprod(a)[9999999:10000000]) user system elapsed 1.97 0.04 2.00 > shall be a little bit quicker then for cycle. But it is valid only for the above calculation. Regards Petr > > > By the way, I'm using R-2.7.2 on Win XP and/or Fedora Linux. > > Thank's in advance for any hints, > Wolfgang Raffelsberger > > . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . > Wolfgang Raffelsberger, PhD > Laboratoire de BioInformatique et Génomique Intégratives > CNRS UMR7104, IGBMC > 1 rue Laurent Fries, 67404 Illkirch Strasbourg, France > > ______________________________________________ > 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.