difference of two rows
You want to use tapply ?tapply This is a simple example dat = data.frame(a=sample(1:10,100,T),b=rnorm(100,0,1)) tapply(dat$b,dat$a,mean) Hope that helps, Sam
On Wed, Nov 25, 2009 at 11:55 AM, clion <birte_2 at hotmail.com> wrote:
Dear R user, I'd like to calculate the difference of two rows, where "ID" is the same. eg.: I've got the following dataframe: ID YEAR 13 2007 15 2003 15 2006 15 2008 21 2006 21 2007 and I'd like to get the difference, like this: ID YEAR ? ? diff 13 2007 ? ? ?NA 15 2003 ? ? ? 3 15 2006 ? ? ? 2 15 2008 ? ? ?NA 21 2006 ? ? ? 1 21 2007 ? ? ?NA that should be fairly easy...I hope Thanks for any helpful comments B. -- View this message in context: http://old.nabble.com/difference-of-two-rows-tp26515212p26515212.html Sent from the R help mailing list archive at Nabble.com.
______________________________________________ R-help at 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.