Two approaches ?aggregate or the reshape package aggregate(xx$volume, list(day=xx$day), sum)
library(reshape) names(xx)[3] <- "value" cast(xx, day ~ ., sum) --- On Wed, 10/1/08, Max Rausch <[EMAIL PROTECTED]> wrote: > From: Max Rausch <[EMAIL PROTECTED]> > Subject: [R] "group by" functionality in R > To: r-help@r-project.org > Received: Wednesday, October 1, 2008, 9:58 AM > I have a data frame with the following information > > day hour volume > 1 2003-07-18 10 836700 > 2 2003-07-18 11 375000 > 3 2003-07-18 12 60000 > 4 2003-07-18 8 1020000 > 5 2003-07-18 9 390000 > > I have been trying create a new data frame with the > following > > day total_daily_volume > > I can accomplish this by bringing the data to excel and > using a pivot > table but I would like to be able to do in R. I have been > searching for > several hours but I can not figure out how to sum the the > volume of > each day. > > Thanks, > > Max > > ______________________________________________ > 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. ______________________________________________ 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.
