[R] Problem with ddply in the plyr-package: surprising output of a date-column

[Christoph Jäckel]

Hi together,

thank you so much for your help! The problem was indeed the
strptime-function. Replacing that with as.Date solves the problem,
both in the example I provided and in my actual data set.

I think this is a lesson for me to not use types I'm not really
familiar with (POSIXlt in this case).

Thanks again!

Christoph

On Mon, Apr 25, 2011 at 10:07 PM, Hadley Wickham <hadley at rice.edu> wrote:
>
> > If you need plyr for other tasks you ought to use a different
> > class for your date data (or wait until plyr can deal with
> > POSIXlt objects).
>
> How do you get POSIXlt objects into a data frame?
>
> > df <- data.frame(x = as.POSIXlt(as.Date(c("2008-01-01"))))
> > str(df)
> 'data.frame':   1 obs. of  1 variable:
>  $ x: POSIXct, format: "2008-01-01"
>
> > df <- data.frame(x = I(as.POSIXlt(as.Date(c("2008-01-01")))))
> > str(df)
> 'data.frame':   1 obs. of  1 variable:
>  $ x: AsIs, format: "0"
>
> Hadley
>
> --
> Assistant Professor / Dobelman Family Junior Chair
> Department of Statistics / Rice University
> http://had.co.nz/



--
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Christoph Jäckel (Dipl.-Kfm.)

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Research Assistant

Chair for Financial Management and Capital Markets | Lehrstuhl für
Finanzmanagement und Kapitalmärkte

TUM School of Management | Technische Universität München

Arcisstr. 21 | D-80333 München | Germany

Mailto: christoph.jaeckel at wi.tum.de | Web: www.fm.wi.tum.de

Phone: +49 89 289 25482 | Fax: +49 89 289 25488



Head of Chair:

Univ.-Prof. Dr. Christoph Kaserer

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