I do the following for a subsetted dataframe: cleanfactors <- function(mydf){ outdf<-mydf for (i in 1:dim(mydf)[2]){ if (is.factor(mydf[,i])) outdf[,i]<-factor(mydf[,i]) } outdf }
Antje wrote: > Hello, > > I hope this question is not too stupid. I would like to know how to > update levels after subsetting data from a data.frame. > > df <- data.frame(factor(c("a","a","c","b","b")), c(4,5,6,7,8), > c(9,1,2,3,4)) > names(df) <- c("X1","X2","X3") > > my.sub <- subset(df, X1 == "a" | X1 == "b") > levels(my.sub$X1) > > # still gives me "a","b","c", though the subset does not contain entries > with "c" anymore > > I guess, the solution is rather simple, but I cannot find it. > > Antje > > ______________________________________________ > 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. > > > ------------------------------------------------------------------------ > > > No virus found in this incoming message. > Checked by AVG - http://www.avg.com > Version: 8.0.176 / Virus Database: 270.9.14/1831 - Release Date: 12/4/2008 > 9:55 PM > -- Erich Neuwirth, University of Vienna Faculty of Computer Science Computer Supported Didactics Working Group Visit our SunSITE at http://sunsite.univie.ac.at Phone: +43-1-4277-39464 Fax: +43-1-4277-39459 ______________________________________________ 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.