Re: [Rd] Date conversion with as.POSIXct and as.POSIXlt (PR#9196)

From: Prof Brian Ripley <>
Date: Fri 01 Sep 2006 - 10:43:54 GMT

On Fri, 1 Sep 2006, Peter Dalgaard wrote:


> I'm not sure any of this is actual bugs (Brian will tell us soon
> enough), but it does appear at least to be underdocumented.

(Your message crossed mine.)

I think it is not a bug and actually explicitly documented in ?as.POSIXlt. What may help those who have not read that documentation is to stick the UTC timezone on the conversion to POSIXlt. Getting

> as.POSIXlt(Sys.Date())

[1] "2006-09-01 UTC"
> as.POSIXct(as.POSIXlt(Sys.Date()))

[1] "2006-09-01 UTC"

> as.POSIXct(as.POSIXlt(Sys.Date()), tz="")
[1] "2006-09-01 01:00:00 GMT Daylight Time"

might be helpful to non-readers.

Brian D. Ripley,        
Professor of Applied Statistics,
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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