Puting my 2cents:

newDF<-data.frame(aggregate(X$PL_Pos, list(X$MyDate), sum))
colnames(newDF)<-c("MyDate","PL_Pos_SUM")
good luck

milton
On Fri, Aug 28, 2009 at 1:03 PM, jim holtman <jholtman@gmail.com> wrote:

> Is this what you want:
>
> > aggregate(X$PL_Pos, list(X$MyDate), sum)
>      Group.1    x
> 1  2009-08-03  174
> 2  2009-08-04  -26
> 3  2009-08-05  614
> 4  2009-08-06  318
> 5  2009-08-10  414
> 6  2009-08-11 -626
> 7  2009-08-12  544
> 8  2009-08-13 -106
> 9  2009-08-17 -146
> 10 2009-08-19 1004
> 11 2009-08-20  568
> 12 2009-08-24 -716
> 13 2009-08-25 -132
> 14 2009-08-26    8
> 15 2009-08-27  622
> >
>  You can fix up the column names.
>
> On Fri, Aug 28, 2009 at 12:37 PM, Mark Knecht<markknecht@gmail.com> wrote:
> > Hi,
> >   I wonder if someone can suggest how to create a new data.frame Y
> > from X where X$PL_Pos is summed by each unique X$MyDate. Y should end
> > up with two (or more) columns Y$MyDate and Y$PL_Sum with its value
> > being the cumsum of all the values in X for that date. - a 'daily
> > cumsum'.
> >
> > Thanks,
> > Mark
> >
> >
> > TStoDate = function (TSDate) {
> >        X = strptime(TSDate + 19e6L, "%Y%m%d")
> >        return(as.Date(X))
> > }
> >
> > X = structure(list(EnDate = c(1090803,
> > 1090804, 1090805, 1090806, 1090806, 1090810, 1090811, 1090812,
> > 1090813, 1090817, 1090819, 1090820, 1090820, 1090824, 1090825,
> > 1090825, 1090826, 1090826, 1090827, 1090827, 1090827), PL_Pos = c(174,
> > -26, 614, 344, -26, 414, -626, 544, -106, -146, 1004, 344, 224,
> > -716, -176, 44, 354, -346, -296, 564, 354)), .Names = c("EnDate",
> "PL_Pos"),
> > class = "data.frame", row.names = c("733",
> > "734", "3631", "3641", "736", "2403", "2413", "3651", "3661",
> > "3671", "3681", "3691", "1303", "3701", "1304", "1305", "2432",
> > "1306", "3712", "1307", "4214"))
> >
> > X$MyDate = TStoDate(X$EnDate)
> >
> > X
> >
> > ______________________________________________
> > 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<http://www.r-project.org/posting-guide.html>
> > and provide commented, minimal, self-contained, reproducible code.
> >
>
>
>
> --
> Jim Holtman
> Cincinnati, OH
> +1 513 646 9390
>
> What is the problem that you are trying to solve?
>
> ______________________________________________
> 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<http://www.r-project.org/posting-guide.html>
> and provide commented, minimal, self-contained, reproducible code.
>

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