Here is an example that may help. I found the idea somewhere in the R-help archives but don't have a reference any more.
mydata <- data.frame(a1 = 1:5, a2 = 2:6, a3 = 3:7) str(mydata) mydata[, 1:2] <- lapply(mydata[,1:2], factor) str(mydata) so basically all you need to do is specific what columns you want to convert to factors and use lapply. Good luck and BTW Rcmdr is a nice GUI but it is much more effiient in the long run to use a command line interface, combinded with a good text editior (Tinn-R is nice for Windows) John Kane Kingston ON Canada > -----Original Message----- > From: xinxi...@163.com > Sent: Tue, 8 May 2012 20:01:28 +0300 > To: r-help@r-project.org > Subject: [R] convert 400 numeric variables to categorical together > > > > > > > Hi Jim and Michael, > > Thank you very much for replying. > > Here is the information about my data. I have a data frame, including > more than 800 variables(columns) and 30000 cases(rows).400 of those > variables are categorical variables. I used to use Rcmdr to convert > variables, however, when the number of variables I need to convert > getting more, I need to keep left clicking mouse to confirm the > conversion (400 times) because as.factor() can only convert 1 variable at > a time. So I am thinking if there is any faster way. Thank you very much. > > Best regards, > > ya > > > > ya > > From: R. Michael Weylandt > Date: 2012-05-08 19:35 > To: xinxi813 > CC: r-help > Subject: Re: [R] convert 400 numeric variables to categorical together > How are they arranged currently? And should they be all one set of > levels or different factor sets? > > Michael > > On Tue, May 8, 2012 at 12:32 PM, ya <xinxi...@163.com> wrote: >> Hi everyone, >> >> Is there anyway I can convert more than 400 numeric variables to >> categorical variables simultaneously? >> >> as.factor() is really slow, and only one at a time. >> >> Thank you very much. >> >> ya >> [[alternative HTML version deleted]] >> >> ______________________________________________ >> 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. > [[alternative HTML version deleted]] > > ______________________________________________ > 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. ____________________________________________________________ GET FREE SMILEYS FOR YOUR IM & EMAIL - Learn more at http://www.inbox.com/smileys Works with AIM®, MSN® Messenger, Yahoo!® Messenger, ICQ®, Google Talk™ and most webmails ______________________________________________ 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.