Hadley Wickham wrote: > On Thu, Feb 4, 2010 at 12:03 PM, Hadley Wickham <had...@rice.edu> wrote: >>> I'd propose the following: If the sets of levels of all arguments are the >>> same, then c.factor() would return a factor with the common set of levels; >>> if the sets of levels differ, then, as Hadley suggests, the level-set of the >>> result would be the union of sets of levels of the arguments, but a warning >>> would be issued. >> I like this compromise (as long as there was an argument to suppress >> the warning) > > If I provided code to do this, along with the warnings for ordered > factors and using the optimisation suggested by Matthew, is there any > member of R core would be interested in sponsoring it? > > Hadley >
Messing with c() is a bit unattractive (I'm not too happy with the other c methods either; normally c() strips attributes and reduces to the base class, and those obviously do not), but a more general concat() function has been suggested a number of times. With a suitable range of methods, this could also be used to reimplement rbind.data.frame (which, incidentally, already contains a method for concatenating factors, with several ugly warts!) -- O__ ---- Peter Dalgaard Ă˜ster Farimagsgade 5, Entr.B c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~~~~~~~~~ - (p.dalga...@biostat.ku.dk) FAX: (+45) 35327907 ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel