[R] "group by" functionality in R

[jim holtman]

?aggregate

         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
> aggregate(x$volume, list(x$day), sum)
     Group.1       x
1 2003-07-18 2681700


On Wed, Oct 1, 2008 at 9:58 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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>



-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

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