On Fri, 2006-12-01 at 12:13 +0100, Peter Dalgaard wrote: > Gavin Simpson wrote: <snip /> > > > > I just don't understand what is going on with data.frame. > > > > > I think there is something about the data you're not telling us...
Yes, that I was doing something very, very silly that I thought would work (produce a vector CLmaxN of the required length), but was in fact blowing out to a huge named list. It was this that was causing the massive increase in computation time in data.frame over cbind. After correcting my mistake, timings for data.frame are: system.time(fab <- data.frame(lc.ratio, Q, + fNupt, + rho.n, rho.s, + net.Nimm, + net.Nden, + CLminN, + CLmaxN, + CLmaxS)) [1] 0.012 0.000 0.011 0.000 0.000 Browse[1]> system.time(fab <- data.frame(lc.ratio = lc.ratio, Q = Q, + fNupt = fNupt, + rho.n = rho.n, rho.s = rho.s, + net.Nimm = net.Nimm, + net.Nden = net.Nden, + CLminN = CLminN, + CLmaxN = CLmaxN, + CLmaxS = CLmaxS)) [1] 0.008 0.000 0.018 0.000 0.000 One vector has names for some reason, removing them brings the un-named data.frame version down to the named version timing and makes no difference to the named version Browse[1]> names(CLmaxS) <- NULL Browse[1]> system.time(fab <- data.frame(lc.ratio, Q, + fNupt, + rho.n, rho.s, + net.Nimm, + net.Nden, + CLminN, + CLmaxN, + CLmaxS)) [1] 0.008 0.000 0.016 0.000 0.000 Browse[1]> system.time(fab <- data.frame(lc.ratio = lc.ratio, Q = Q, + fNupt = fNupt, + rho.n = rho.n, rho.s = rho.s, + net.Nimm = net.Nimm, + net.Nden = net.Nden, + CLminN = CLminN, + CLmaxN = CLmaxN, + CLmaxS = CLmaxS)) [1] 0.008 0.000 0.009 0.000 0.000 Apologies to the list for bothering you all with my stupidity and thank you again to everyone who replied - I knew it was I who was doing something wrong, but couldn't see it and thanks to your comments, suggestions and queries I was able to work out what that was. All the best, G -- %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% Gavin Simpson [t] +44 (0)20 7679 0522 ECRC & ENSIS, UCL Geography, [f] +44 (0)20 7679 0565 Pearson Building, [e] gavin.simpsonATNOSPAMucl.ac.uk Gower Street, London [w] http://www.ucl.ac.uk/~ucfagls/ UK. WC1E 6BT. [w] http://www.freshwaters.org.uk %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% ______________________________________________ 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 and provide commented, minimal, self-contained, reproducible code.
