Thanks Greg, Jorge, and Jim for your help. Peng
On Thu, Dec 3, 2009 at 1:58 PM, jim holtman <jholt...@gmail.com> wrote: > try this: > > > x > State Month Year Value > 1 NC Jan 1996 1 > 2 NC Jan 1996 2 > 3 NC Feb 1997 2 > 4 NC Feb 1997 3 > 5 NC Mar 1998 3 > 6 NC Mar 1998 4 > 7 NY Jan 1996 4 > 8 NY Jan 1996 5 > 9 NY Feb 1997 5 > 10 NY Feb 1997 6 > 11 NY Mar 1998 6 > 12 NY Mar 1998 7 > > tapply(x$Value, list(x$State, x$Year), sum) > 1996 1997 1998 > NC 3 5 7 > NY 9 11 13 > > > > tapply(x$Value, list(x$State, x$Year, x$Month), sum) > , , Feb > 1996 1997 1998 > NC NA 5 NA > NY NA 11 NA > , , Jan > 1996 1997 1998 > NC 3 NA NA > NY 9 NA NA > , , Mar > 1996 1997 1998 > NC NA NA 7 > NY NA NA 13 > > > > > > On Thu, Dec 3, 2009 at 1:50 PM, Peng Cai <pengcaimaill...@gmail.com>wrote: > >> Hi R Users, >> >> I'm wondering how can I calculate two (or three) way sum of a variable. A >> sample data is: >> >> State Month Year Value >> NC Jan 1996 1 >> NC Jan 1996 2 >> NC Feb 1997 2 >> NC Feb 1997 3 >> NC Mar 1998 3 >> NC Mar 1998 4 >> NY Jan 1996 4 >> NY Jan 1996 5 >> NY Feb 1997 5 >> NY Feb 1997 6 >> NY Mar 1998 6 >> NY Mar 1998 7 >> >> I'm trying to sum up "value" column by State*Month and by >> State*Month*Year. >> Also, I may need to calculate mean value along with "sum". >> >> Any help would be greatly appreciated, >> >> Thanks, >> Peng >> >> [[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<http://www.r-project.org/posting-guide.html> >> and provide commented, minimal, self-contained, reproducible code. >> > > > > -- > Jim Holtman > Cincinnati, OH > +1 513 646 9390 > > What is the problem that you are trying to solve? > [[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.
