strings <- replicate(1e5, paste(sample(letters, 100, rep = T), collapse = "")) system.time(strings[-1] == strings[-1e5]) # user system elapsed # 0.016 0.000 0.017
So it takes ~1/100 of a second to do ~100,000 string comparisons. You need to provide a reproducible example that illustrates why you think string comparisons are slow. Hadley On Tue, Jul 13, 2010 at 6:52 AM, Ralf B <ralf.bie...@gmail.com> wrote: > I am asking this question because String comparison in R seems to be > awfully slow (based on profiling results) and I wonder if perhaps '==' > alone is not the best one can do. I did not ask for anything > particular and I don't think I need to provide a self-contained source > example for the question. So, to re-phrase my question, are there more > (runtime) effective ways to find out if two strings (about 100-150 > characters long) are equal? > > Ralf > > > > > > > On Sun, Jul 11, 2010 at 2:37 PM, Sharpie <ch...@sharpsteen.net> wrote: >> >> >> Ralf B wrote: >>> >>> What is the fastest way to compare two strings in R? >>> >>> Ralf >>> >> >> Which way is not fast enough? >> >> In other words, are you asking this question because profiling showed one of >> R's string comparison operations is causing a massive bottleneck in your >> code? If so, which one and how are you using it? >> >> -Charlie >> >> ----- >> Charlie Sharpsteen >> Undergraduate-- Environmental Resources Engineering >> Humboldt State University >> -- >> View this message in context: >> http://r.789695.n4.nabble.com/Fast-string-comparison-tp2285156p2285409.html >> Sent from the R help mailing list archive at Nabble.com. >> >> ______________________________________________ >> 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. >> > > ______________________________________________ > 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. > -- Assistant Professor / Dobelman Family Junior Chair Department of Statistics / Rice University 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.
