try this: > 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$X1) [1] "a" "b" "c" > my.sub$X1 <- factor(my.sub$X1) > levels(my.sub$X1) [1] "a" "b" >
On Fri, Dec 5, 2008 at 7:50 AM, Antje <[EMAIL PROTECTED]> 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. > -- Jim Holtman Cincinnati, OH +1 513 646 9390 What is the problem that you are trying to solve? ______________________________________________ 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.