Makes sense, thanks for the explanation. Best, Ista
On Sat, Jun 21, 2014 at 3:56 AM, Prof Brian Ripley <rip...@stats.ox.ac.uk> wrote: > On 20/06/2014 15:37, Ista Zahn wrote: >> >> Hello, >> >> I've noticed that dget() is much slower in the current and devel R >> versions than in previous versions. In 2.15 reading a 10000-row >> data.frame takes less than half a second: >> >>> (which.r <- R.Version()$version.string) >> >> [1] "R version 2.15.2 (2012-10-26)" >>> >>> x <- data.frame(matrix(sample(letters, 100000, replace = TRUE), ncol = >>> 10)) >>> dput(x, which.r) >>> system.time(y <- dget(which.r)) >> >> user system elapsed >> 0.546 0.033 0.586 >> >> While in 3.1.0 and r-devel it takes around 7 seconds. >> >>> (which.r <- R.Version()$version.string) >> >> [1] "R version 3.1.0 (2014-04-10)" >>> >>> x <- data.frame(matrix(sample(letters, 100000, replace = TRUE), ncol = >>> 10)) >>> dput(x, which.r) >>> system.time(y <- dget(which.r)) >> >> user system elapsed >> 6.920 0.060 7.074 >> >>> (which.r <- R.Version()$version.string) >> >> [1] "R Under development (unstable) (2014-06-19 r65979)" >>> >>> x <- data.frame(matrix(sample(letters, 100000, replace = TRUE), ncol = >>> 10)) >>> dput(x, which.r) >>> system.time(y <- dget(which.r)) >> >> user system elapsed >> 6.886 0.047 6.943 >>> >>> >> >> I know dput/dget is probably not the right tool for this job: >> nevertheless the slowdown in quite dramatic so I thought it was worth >> calling attention to. > > > This is completely the wrong way to do this. See ?dump. > > dget() basically calls eval(parse()). parse() is much slower in R >= 3.0 > mainly because it keeps more information. Using keep.source=FALSE here > speeds things up a lot. > > >> system.time(y <- dget(which.r)) > user system elapsed > 3.233 0.012 3.248 >> options(keep.source=FALSE) > >> system.time(y <- dget(which.r)) > user system elapsed > 0.090 0.001 0.092 > > > -- > Brian D. Ripley, rip...@stats.ox.ac.uk > Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ > University of Oxford, Tel: +44 1865 272861 (self) > 1 South Parks Road, +44 1865 272866 (PA) > Oxford OX1 3TG, UK Fax: +44 1865 272595 ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
