On 4 Jul 2005, at 15:15, Peter Dalgaard wrote: > > Your original code got lost in the threading, but that order of > magnitude suggests that you have N^2/2 behaviour somewhere. The > typical > culprit is code like > > x <- numeric(0) > for (i in 1:N){ > newx <- <<....>> > x <- c(x, newx) > } > > in which the extension of x causes the whole thing to be reallocated > and copied. Same thing with cbind and rbind constructs of course.
I changed my code a bit, and now the runtime is dow to less than a minute (from more than 24 hours). I was copying a large dataset many times over, when I extracted the columns I need as independet vectors runtime dropped like a stone. Cheers, Federico -- Federico C. F. Calboli Department of Epidemiology and Public Health Imperial College, St. Mary's Campus Norfolk Place, London W2 1PG Tel +44 (0)20 75941602 Fax +44 (0)20 75943193 f.calboli [.a.t] imperial.ac.uk f.calboli [.a.t] gmail.com ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html