It's not very clear from what you pasted into your message what your data frame looks like. Does it always have 2 lines per record or just one? Also - in what format is your YEAR?
On Wed, Apr 21, 2010 at 9:54 AM, n.via...@libero.it <n.via...@libero.it> wrote: > Dear list, > I have a question about the selection of Variables in dataframes. > I have a dataframes like this: > > CFISCA FIRMS > YEAR VAR VALUE > 20345 nike > 2005 EC01 34 > 20345 nike > 2006 EC01 45 > 56779 mediaset > 2005 EC01 65 > 64568 agazzini > 2005 EC01 78 > 64568 agazzini > 2006 EC01 56 > 78907 uniteam > 2006 EC01 46 > > > what my result should be is a new dataframes which have only firms which have > data in both years (2005,2006) > > CFISCA FIRMS > YEAR VAR VALUE > 20345 nike > 2005 EC01 34 > 20345 nike > 2006 EC01 45 > 64568 agazzini > 2005 EC01 78 > 64568 agazzini > 2006 EC01 56 > > > Thanks for your attention!!! > > ______________________________________________ > 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. > -- Dimitri Liakhovitski Ninah.com dimitri.liakhovit...@ninah.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.