[R] "group by" functionality in R

[Henrique Dallazuanna]

Try this also;

 xtabs(volume ~ day, data = x)

On Wed, Oct 1, 2008 at 10:58 AM, 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.
>
> Thanks,
>
> Max
>
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>



-- 
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O