Nevermind, I found the fix. Declaring the length for out eliminates the performance decrease, out <- vector(mode="numeric",length=length(test))
On 10/10/05, bogdan romocea <[EMAIL PROTECTED]> wrote: > Dear useRs, > > I'm wondering why the for() loop below runs slower as it progresses. > On a Win XP box, the iterations at the beginning run much faster than > those at the end: > 1%, iteration 2000, 10:10:16 > 2%, iteration 4000, 10:10:17 > 3%, iteration 6000, 10:10:17 > 98%, iteration 196000, 10:24:04 > 99%, iteration 198000, 10:24:24 > 100%, iteration 200000, 10:24:38 > > Is there something that can be done about this? Would such a loop run > faster in C/C++/Fortran? > > Thank you, > b. > > #---sample code > loop.progress <- function(loop,iterations,steps,toprint=NULL) > { > marks <- c(1,floor(iterations/steps)*(1:steps)) > if (loop %in% marks) { > if (is.null(toprint)) prt <- loop else prt <- toprint > cat(paste(round((which(marks == loop)-1)*(100/steps),0),"%, iteration > ", > prt,", ",format(Sys.time(),"%H:%M:%S"),sep=""),"\n") > } > } > #---loop that runs slower and slower > test <- runif(200000) > out <- vector(mode="numeric") > lg <- 30 > for (i in (lg+1):length(test)) > { > loop.progress(i,length(test),100) > out[i] <- sum(test[(i-lg):i]) > } > ______________________________________________ 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