Dear Hilmar, You could use something like
DF <- as.data.frame(lapply(DF, function (x) if (is.factor(x)) factor(x) else x)) Where DF is the data frame. I hope this helps, John -------------------------------- John Fox, Professor Department of Sociology McMaster University Hamilton, Ontario Canada L8S 4M4 905-525-9140x23604 http://socserv.mcmaster.ca/jfox -------------------------------- > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Hilmar Berger > Sent: Tuesday, June 05, 2007 8:20 AM > To: [email protected] > Subject: [R] Refactor all factors in a data frame > > Hi all, > > Assume I have a data frame with numerical and factor > variables that I got through merging various other data > frames and subsetting the resulting data frame afterwards. > The number levels of the factors seem to be the same as in > the original data frames, probably because subset() calls > [.factor without drop = TRUE (that's what I gather from > scanning the mailing lists). > > I wonder if there is a easy way to refactor all factors in > the data frame at once. I noted that fix(data_frame) does the > trick, however, this needs user interaction, which I'd like > to avoid. Subsequent write.table / read.table would be > another option but I'm not sure if R can guess the > factor/char/numeric-type correctly when reading the table. > > So, is there any way in drop the unused factor levels from > *all* factors of a data frame without import/export ? > > Thanks in advance, > Hilmar > > -- > > Hilmar Berger > Studienkoordinator > Institut für medizinische Informatik, Statistik und > Epidemiologie Universität Leipzig Härtelstr. 16-18 > D-04107 Leipzig > > Tel. +49 341 97 16 101 > Fax. +49 341 97 16 109 > email: [EMAIL PROTECTED] > > ______________________________________________ > [email protected] 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. > ______________________________________________ [email protected] 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.
