Hi. See http://stackoverflow.com/questions/1995933/number-of-months-between-two-dates
Andrija On Thu, Jul 11, 2013 at 11:56 AM, Gallon Li <gallon...@gmail.com> wrote: > My data are from 2008 to 2010, with repeated measures for same subjects. I > wish to compute number of months since january 2008. > > The data are like the following: > > ID date > 1 4/12/2008 > 1 4/13/2008 > 1 5/11/2008 > 2 3/21/2009 > 2 4/22/2009 > 2 8/05/2009 > ... > > the date column are in the format "%m/%d/%y". i wish to obtain > > ID month > 1 4 > 1 4 > 1 5 > 2 15 > 2 16 > 2 20 > ... > > also, for the same ID with two identical month, I only want to keep the > last one. can any expert help with this question? > > [[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. > [[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.
