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<markkne...@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
>
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> PLEASE do read the posting guide 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?
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