[Rd] R4.1: seq.POSIXt, tz="AEST" (PR#9572)
ripley at stats.ox.ac.uk
ripley at stats.ox.ac.uk
Mon Mar 19 13:03:42 CET 2007
Hmm, AEST is not a valid time zone on Windows.
See ?as.POSIXlt for one of several places where this is documented.
But in any case, the underlying problem is in the OS, and we only try to
work around it to the best of our knowledge (and that excludes
undocumented time zones).
On Mon, 19 Mar 2007, felix at nfrac.org wrote:
> Times from seq.POSIXt come out wrong in AEST timezone around Feb 29 every
> leap year before 1970 (on Windows XP).
>
> According to help(DateTimeClasses), this is handled by "our own C code".
>
>> x <- as.POSIXct("1968-02-27") # tz="AEST"
>> x.gmt <- as.POSIXct("1968-02-27", tz="GMT")
>> data.frame(
> GMT=seq(x.gmt, by="day", length=8),
> byday=seq(x, by="day", length=8),
> byDST=seq(x, by="DSTday", length=8))
> GMT byday byDST
> 1 1968-02-27 1968-02-27 1968-02-27
> 2 1968-02-28 1968-02-28 1968-02-28
> 3 1968-02-29 1968-03-01 1968-03-02
> 4 1968-03-01 1968-03-02 1968-03-02
> 5 1968-03-02 1968-03-02 1968-03-02
> 6 1968-03-03 1968-03-03 1968-03-03
> 7 1968-03-04 1968-03-04 1968-03-04
> 8 1968-03-05 1968-03-05 1968-03-05
>
>> R.version
> _
> platform i386-pc-mingw32
> arch i386
> os mingw32
> system i386, mingw32
> status
> major 2
> minor 4.1
> year 2006
> month 12
> day 18
> svn rev 40228
> language R
> version.string R version 2.4.1 (2006-12-18)
>
>
>
>
--
Brian D. Ripley, ripley at stats.ox.ac.uk
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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