tapply(df$Date, df$SomeFactor, max, simplify=FALSE) works, i.e. it is the unlist() which is losing the class (and perhaps unlist or tapply should be a bit cleverer).
On Mon, 30 Jan 2006, David Randel wrote: > I have a column in a data frame that has a class of "Date" and a mode of > "numeric". When I: > > max(df$Date) > > My output stays in Date format, i.e. "2006-01-03". > > However, when I run the following statment: > > tapply(df$Date, df$SomeFactor, max) > > my output looks like this: 9129 9493 9861 10226 10591 10956 11320 > 11687 12052 12417 > > The returned object is of mode "numeric" and class "array". Each array > element is of mode "numeric" and class "numeric". I believe that this is > the integer representation of my date. I can't seem to convert it back to a > date. > > How do I get these to be intrepreted as a date instead of a number? > > Thanks, > ~Dave R. > > ______________________________________________ > [email protected] mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html > -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595 ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
