[R] "group by" functionality in R
csardi.gabor at gmail.com
Wed Oct 1 17:59:16 CEST 2008
tapply(data$volume, data$day, sum)
would do I think. But I haven't tried, was to lazy to type in some
data, I'm sorry.
On Wed, Oct 1, 2008 at 3:58 PM, Max Rausch <maxrausch at gmail.com> wrote:
> 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.
> R-help at r-project.org mailing list
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
Gabor Csardi <Gabor.Csardi at unil.ch> UNIL DGM
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