On May 7, 2011, at 17:21 , Hadley Wickham wrote: >> >> Well, ave() uses interaction(...) and interaction() has a "drop" argument, so >> >>> with(x, ave(H, Site, Prof, drop=TRUE, FUN=function(y)y-min(y))) >> [1] 8 0 51 0 33 22 21 0 > > I don't understand why this isn't the default. > > Hadley
Defensive programming, maybe? It's not the default for interaction(), which makes sense, and if you pass a non-default option, you cannot revert it. Not that I can think up a case where you'd actually want to process the empty levels either. -- Peter Dalgaard Center for Statistics, Copenhagen Business School Solbjerg Plads 3, 2000 Frederiksberg, Denmark Phone: (+45)38153501 Email: pd....@cbs.dk Priv: pda...@gmail.com ______________________________________________ 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.
