Hi Daren, Unfortunately, the current version of reshape isn't very efficient. I'm working on a new version which should be 10-20x times faster for the operation that you're performing, but this won't be ready for a while and in the meantime you might want to try an alternative approach, like the one that Gabor suggested.
Hadley On Tue, Dec 2, 2008 at 10:52 PM, Daren Tan <[EMAIL PROTECTED]> wrote: > > Hi, > > I am casting a dataframe from long to wide format. The same codes that works > for a smaller dataframe would take a long time (more than two hours and still > running) for a longer dataframe of 2495227 rows and ten different predictors. > How to make it more efficient ? > > wer <- data.frame(Name=c(1:5, 4:5), Type=c(letters[1:5], letters[4:5]), > Predictor=c("A", "A", "A", "A", "A", "B", "B")) >> wer > Name Type Predictor > 1 1 a A > 2 2 b A > 3 3 c A > 4 4 d A > 5 5 e A > 6 4 d B > 7 5 e B > > wer.melt <- melt(wer, id.var=c("Name", "Type")) > > cast(wer.melt, Name + Type ~ value, length, fill=0) > Name Type A B > 1 1 a 1 0 > 2 2 b 1 0 > 3 3 c 1 0 > 4 4 d 1 1 > 5 5 e 1 1 > >> sessionInfo() > R version 2.7.0 (2008-04-22) > x86_64-unknown-linux-gnu > locale: > LC_CTYPE=en_US.UTF-8;LC_NUMERIC=C;LC_TIME=en_US.UTF-8;LC_COLLATE=en_US.UTF-8;LC_MONETARY=C;LC_MESSAGES=en_US.UTF-8;LC_PAPER=en_US.UTF-8;LC_NAME=C;LC_ADDRESS=C;LC_TELEPHONE=C;LC_MEASUREMENT=en_US.UTF-8;LC_IDENTIFICATION=C > attached base packages: > [1] stats graphics grDevices utils datasets methods base > other attached packages: > [1] reshape_0.8.0 > > ______________________________________________ > 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. > -- http://had.co.nz/ ______________________________________________ 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.