On Thu, Jan 17, 2013 at 9:54 PM, John Merrill <john.merr...@gmail.com> wrote: > As of 2.15.1, data.frame appears to no longer be O(n^2) in the number of > columns in the frame. That's certainly an improvement, yes. > > However, by eliminating calls to data.frame and replacing them with direct > class modifications, I can take a routine which takes minutes and reduce it > to a routine which takes seconds. So, pragmatically, in Rcpp, I can get a > rough factor of sixty, it appears. > > Wow.
When you have this written out, will you post links to it? I can learn from your examples, I think. pj > On Thu, Jan 17, 2013 at 7:46 PM, Paul Johnson <pauljoh...@gmail.com> wrote: >> >> On Tue, Jan 15, 2013 at 9:20 AM, John Merrill <john.merr...@gmail.com> >> wrote: >> > It appears that DataFrame::create is a thin layer on top of the R >> > data.frame >> > call. The guarantee correctness, but also means the performance of an >> > Rcpp >> > routine which returns a large data frame is limited by the performance >> > of >> > data.frame -- which is utterly horrible. >> >> Are you certain that this claim is still true? >> >> I was shocked/surprised by the package "dataframe" and the commentary >> about it. The author said that data.frame was slow because "This >> contains versions of standard data frame functions in R, modified to >> avoid making extra copies of inputs. This is faster, particularly for >> large data." >> >> it was repeatedly copying some objects and he proved a substantially >> faster approach. >> >> In the release notes for R-2.15.1, I recall seeing a note that R Core >> had responded by integrating several of those changes. But still >> data.frame is not fast for you? >> >> If they didn't make the core data.frame as fast, would you care to >> enlighten us by installing the dataframe package and letting us know >> if it is still faster? >> >> Or perhaps you are way ahead of me and you've already imitated >> Hesterberg's algorithms in your C++ design? >> >> pj >> >> -- >> Paul E. Johnson >> Professor, Political Science Assoc. Director >> 1541 Lilac Lane, Room 504 Center for Research Methods >> University of Kansas University of Kansas >> http://pj.freefaculty.org http://quant.ku.edu > > -- Paul E. Johnson Professor, Political Science Assoc. Director 1541 Lilac Lane, Room 504 Center for Research Methods University of Kansas University of Kansas http://pj.freefaculty.org http://quant.ku.edu _______________________________________________ Rcpp-devel mailing list Rcpp-devel@lists.r-forge.r-project.org https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel
