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

From: Hadley Wickham <>
Date: Mon, 25 Apr 2011 15:07:41 -0500

> 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"


Assistant Professor / Dobelman Family Junior Chair
Department of Statistics / Rice University

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Received on Mon 25 Apr 2011 - 20:10:08 GMT

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