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

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

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 J?ckel (Dipl.-Kfm.)

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Research Assistant

Chair for Financial Management and Capital Markets | Lehrstuhl f?r
Finanzmanagement und Kapitalm?rkte

TUM School of Management | Technische Universit?t M?nchen

Arcisstr. 21 | D-80333 M?nchen | 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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