On Tue, Jan 13, 2009 at 8:28 AM, Terry Therneau <thern...@mayo.edu> wrote: > Thanks for the replies: > > Duncan: >> and got a warning in all R versions I tried back to 2.4.1. In 2.3.1 >> this was an error. > > It seems I have egg on my face wrt this point. A more true synopsis of what > I > saw should have been that 1. I've never noticed this in R before and 2. Until > recently I did all my modeling in Splus or Bell S, and character vectors > always > worked there. (My survival routines were always more up to date in Splus > because that's what I use for the source code. But conversion from a local > cvs > archive to Rforge is nearly done -- just a survexp.us ratetable issue remains > -- > so R will become my most current version in another day or two.) Possibly I > don't have any character variables as covariates in the survival test suite. > > > Hadley: >> I think R's handling of character vectors has progressed to the point >> where they should be the norm, not the exception. Maybe others will >> have different views. > > Factors are very useful when there is a small discrete number of levels, and > I > use them moderately often. For that case, most of the default behavior of > factors makes perfect sense, e.g., retention of levels. I'm very sure that > adding stringsAsFactors to the system options was a good thing, not as sure > that > defaulting it to FALSE is the best thing for all users. > In my world most of the data comes from formal processes: clinical trials, > data bases, large studies that use dedicated keyed entry, etc. The most > common > character variables are things like id, name, and address for which the factor > paradym doesn't work, and most of the variables I get that are actually > 'factors' come to me as small integers; I turn them into factors using both > the > levels and labels arguments. Thus autoconversion is just a PITA. But my world > is not everyone's. > My main complaint with factors has always been the assumption that > everything > should be turned into one. I fought that battle with Splus. Defaults > behavior
See the stringsAsFactors option in ?options to change the global default. ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
