Hi, I think you just need to add the format = argument. Does this help?
> x <- factor("01-11-2007") > as.character(x) [1] "01-11-2007" > as.Date(as.character(x), format = "%d-%m-%Y") [1] "2007-11-01" Cheers, Josh On Fri, Sep 3, 2010 at 2:11 PM, André de Boer <rnie...@gmail.com> wrote: > > Hello, > > I have a dataframe with data such as: > > dat$BEGINDATUM[3] > [1] 13-09-2007 > > dat$BEGINDATUM[4] > [1] 01-11-2007 > > > class(dat$BEGINDATUM[3]) > [1] "factor" > > Now I need to make calculation with these dates. > But I get these result: > > as.date(as.character(dat$BEGINDATUM[3])) > [1] <NA> > > as.date(as.character(dat$BEGINDATUM[4])) > [1] 11Jan2007 > > How can i convert these factors to make calculations possible. > > Thanks for the answer, > Andre > > [[alternative HTML version deleted]] > > ______________________________________________ > 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. -- Joshua Wiley Ph.D. Student, Health Psychology University of California, Los Angeles http://www.joshuawiley.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.