This issue has been reported before http://thread.gmane.org/gmane.comp.lang.r.devel/20945/focus=20959
It happens when data frames contain character strings. Thanks, Adrian On Thu, 13 Aug 2009, Simon Urbanek wrote: > Rick, > > I'm sorry, but I cannot reproduce it. You didn't supply sessionInfo() and the > actual data, so all I can do is guess, but according to your description this > test case shows no difference: > > set.seed(1) > n=10000 > d1=data.frame(seqn=as.integer(runif(n)*n),a=rnorm(n),b=rnorm(n),c=rnorm(n),d=rnorm(n),e=rnorm(n),f=rnorm(n),g=rnorm(n),h=rnorm(n),i=rnorm(n)) > d2=data.frame(seqn=as.integer(runif(n)*n),a=rnorm(n),b=rnorm(n),c=rnorm(n),d=rnorm(n),e=rnorm(n),f=rnorm(n),g=rnorm(n),h=rnorm(n),i=rnorm(n)) > system.time(merge(d1,d2,by="seqn",all.x=TRUE)) > > R 2.9.1: >> system.time(merge(d1,d2,by="seqn",all.x=TRUE)) > user system elapsed > 0.150 0.067 0.217 > > R 2.9.0: >> system.time(merge(d1,d2,by="seqn",all.x=TRUE)) > user system elapsed > 0.148 0.068 0.216 > > To substantiate your claim, please provide a reproducible example as well as > sessionInfo() [and details on how you run it - GUI, CLI, ...], but I suspect > the difference may be in your data, not R. > > Thanks, > Simon > > > On Aug 12, 2009, at 12:25 , richard_stahl...@urmc.rochester.edu wrote: > >> Full_Name: Rick Stahlhut >> Version: 2.9.1 >> OS: os x 10.5.7 >> Submission from: (NULL) (128.151.71.23) >> >> >> I upgraded to 2.9.1 today from 2.9.0. I work with large CDC (center for >> disease control) datasets and start, frequently, with a series of 23 >> large-ish >> merges to create the final dataset I work on. I do this each time because >> (a) R >> is fast. why not? and b) the datasets occasionally get updated by CDC >> and >> it's easier to swap in new files that way. >> >> One such merge is two data.frames with 10 variables and 10,000 rows each. >> The >> command in question is: >> >> temp = merge (demo.2,ph,by="seqn",all.x=TRUE) >> >> in 2.9.0, this command took 3.3 seconds. >> in 2.9.1, it took 35.8 seconds. >> >> I have reverted back to 2.9.0. >> >> Additional packages loaded are: >> >> library(Hmisc) >> library(alr3) >> library(epicalc) >> library(ggplot2) >> library(lattice) >> library(reshape) >> library(survey) >> library(car) >> >> thanks very much for all the effort. R is wonderful. >> >> ______________________________________________ >> R-devel@r-project.org mailing list >> https://stat.ethz.ch/mailman/listinfo/r-devel >> >> > > ______________________________________________ > R-devel@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
