Karen levels returns the levels attribute of a variable, and a vector has no such attribute. This is usually used with a factor, e.g.
> temp <- c(3, 5, 5, NA) > levels(factor(temp)) [1] "3" "5" Best wishes Richard Chang Liu wrote: > Hello: > > I'm trying to use levels function, but I don't know why it's returning NULL. > For example: > > >> temp[1] 3 5 5 NA> levels(temp)NULL> >> > > Also, I've tried: > >> list(temp)[[1]][1] "3" "5" "5" NA >> levels(list(temp))NULL >> > Is there a specific requirement on the parameter? > > Karen > > _________________________________________________________________ > > > [[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. > > ______________________________________________ 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.