Hi Adam, A recent thread on R-help deals exactly with your problem. In one of the responses I compare ddply to a number of alternative solutions (using ave and data.table) [1]. The test in the e-mail shows that for large amounts of unique categories, ddply is quite slow. Hadley (Wickham, author of ddply) remarked in reply to a question on the plyr mailing list that this was due to how ddply was setup [2]. So in your case I would definitely take a look at data.table, which is probably much faster. If that does not work, take a look at ave which is also quite a bit faster for your problem.
cheers, Paul [1] http://www.mail-archive.com/r-help@r-project.org/msg142797.html [2] http://groups.google.com/group/manipulatr/browse_thread/thread/5e8dfed85048df99 On 08/24/2011 04:25 PM, AdamMarczak wrote: > Hello everyone, > I was asked to repost this again, sorry for any inconvenience. > > I'm looking replacement for ddply function from plyr package. > Function allows to apply function by category stored in any column/columns. > > Regular loops or lapplys slow down greatly because my unique combination > count exceeds 9000. Is there any available solution which allow me to apply > function by category? > > currently my code looks like snippet below > > ddply(myData, c("country_name", "product_name"), myFunction) > > Please note that I'm looking for decently performing resolution. > > Thanks in advance! > > With regards, > Adam. > > -- > View this message in context: > http://r.789695.n4.nabble.com/ddply-from-plyr-package-any-alternatives-tp3765936p3765936.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. -- Paul Hiemstra, Ph.D. Global Climate Division Royal Netherlands Meteorological Institute (KNMI) Wilhelminalaan 10 | 3732 GK | De Bilt | Kamer B 3.39 P.O. Box 201 | 3730 AE | De Bilt tel: +31 30 2206 494 http://intamap.geo.uu.nl/~paul http://nl.linkedin.com/pub/paul-hiemstra/20/30b/770 ______________________________________________ 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.
