Have you read the Introduction to R tutorial? This is discussed there, I believe. If you have not, please do so before posting here further.
But ... ?tapply ?aggregate ?ave Also the plyr package for "user-friendlier" approaches. -- Bert On Wed, Nov 7, 2012 at 9:32 AM, Keith Weintraub <kw1...@gmail.com> wrote: > Folks, > I have a data frame with columns 200401, 200402, ..., 201207, 201208. > > These represent years/months. What would be the best way to sum these columns > by year? What about by quarter? > > Thanks for your time, > KW > > -- > > > [[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. -- Bert Gunter Genentech Nonclinical Biostatistics Internal Contact Info: Phone: 467-7374 Website: http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm ______________________________________________ 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.
