I'm fairly new to R, coming from a programming background -- it's quite nice to work with dataframes, though, as opposed to explicit iteration.
One thing I've found, which is surprising is that zero-length dataframes seem to cause errors: > t <- data.frame(bob=c(100)) > order(t$bob) [1] 1 > t1 <- t[t$bob < 50] > order(t1$bob) Error in order(na.last, decreasing, ...) : argument 1 is not a vector I'd expect c() as a result, not an error. So I have two questions -- Is there something important I'm misunderstanding? What idioms do experts use to deal with this? Just calling nrow to handle the 0 case? Something cleaner? Thanks, Ranjan ______________________________________________ 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.