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.
