Does not happen on Solaris or Linux, so looks like a MacOS X problem.
Here is some crosschecks:
> unclass(datesTest)
[1] -6301 -6300 -6299
attr(,"format")
[1] "m/d/y"
attr(,"origin")
month day year
1 1 1970
> unclass(as.POSIXct(datesTest))
[1] -544406400 -544320000 -544233600
On Wed, 12 Nov 2003, Brian Beckage wrote:
> Dear R list,
>
> I noticed the following 'problem' when changing the format of dates
> created with seq.dates() (from the Chron library) using as.POSIXct()
> (R 1.8.0 on OSX 10.2.8):
>
> > datesTest<-seq.dates(from="10/01/1952", length=3, by="days");
> > datesTest
> [1] 10/01/52 10/02/52 10/03/52
>
> # Now changing the format to show year as 1952.
>
> > datesTest<-format(as.POSIXct(datesTest), "%m/%d/%Y")
> > datesTest
> [1] "09/30/1952" "10/01/1952" "10/02/1952"
> >
>
> The dates were shifted by one day. The work around is simple enough, e.g.,
>
> > datesTest<-format(as.POSIXct(datesTest+1), "%m/%d/%Y")
> [1] "10/01/1952" "10/02/1952" "10/03/1952"
>
> but I wonder if this is the intended behavior?
>
> Brian
>
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>
--
Brian D. Ripley, [EMAIL PROTECTED]
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
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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