With the approach of R 2.12.0: with mild apologies for re-opening this perennial issue: is there any hope, if appropriate patches are submitted, of adding a drop.levels argument (with default equal to FALSE to preserve backward compatibility/efficiency) to the subset function ... ? If not, would a patch to the documentation and/or the R FAQ be accepted?
This does seem to be a continuing source of confusion/frustration (it certainly is among my students, and here is some documentation from r-help over the years). Note that some of the earliest threads here refer to the problem (now fixed) that the subset() documentation failed to note that the existing 'drop' argument would *not* (confusingly) drop unused levels. http://finzi.psych.upenn.edu/Rhelp10/2008-April/158566.html http://finzi.psych.upenn.edu/R/Rhelp02/archive/42976.html http://finzi.psych.upenn.edu/R/Rhelp02/archive/36961.html http://finzi.psych.upenn.edu/Rhelp10/2009-November/217878.html http://article.gmane.org/gmane.comp.lang.r.general/200395 This suggestion is milder and less wide-ranging than a global drop.unused.levels option, or than convincing everyone to use strings rather than factors most of the time ... cheers Ben Bolker -- Ben Bolker bbol...@gmail.com , bol...@mcmaster.ca http://www.math.mcmaster.ca/~bolker GPG key: http://www.math.mcmaster.ca/~bolker/benbolker-publickey.asc ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
