Incorrect DST time changes in DateTimeClasses

Apologies - I intended to add that info at the end: OS X 10.8.2 and R
2.15.1.

Many thanks.

R.Version()

$platform
[1] "x86_64-apple-darwin9.8.0"
$arch
[1] "x86_64"
$os
[1] "darwin9.8.0"
$system
[1] "x86_64, darwin9.8.0"
$status
[1] ""
$major
[1] "2"
$minor
[1] "15.1"
$year
[1] "2012"
$month
[1] "06"
$day
[1] "22"
$`svn rev`
[1] "59600"
$language
[1] "R"
$version.string
[1] "R version 2.15.1 (2012-06-22)"
$nickname
[1] "Roasted Marshmallows"


On 7/12/2012, at 04:29 , Uwe Ligges <ligges at statistik.tu-dortmund.de>
wrote:

On 06.12.2012 15:54, Jeff Newmiller wrote:

What OS are you using? It makes a difference.

... and R version.

Uwe Ligges

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Sent from my phone. Please excuse my brevity.

Andrew Digby <andrewdigby at mac.com> wrote:

Can anyone please shed any light on why R DateTimeClasses give

weird

times for when daylight saving time information changes, and which
aren't consistent with the OS?

Example:

	Expected result: in New Zealand DST stopped (NZDT -> NZST) at

03:00

NZDT on 2010-04-04, as confirmed by the OS time zone info (OS X
10.8.2):

	zdump -v /etc/localtime
		/etc/localtime  Sat Apr  3 13:59:59 2010 UTC = Sun Apr  4

02:59:59

2010 NZDT isdst=1
		/etc/localtime  Sat Apr  3 14:00:00 2010 UTC = Sun Apr  4

02:00:00

2010 NZST isdst=0

	Result in R: R has DST changing at 02:26:08, instead of 03:00!

	> a<-as.POSIXlt('2010-04-04 02:26:07',tz="NZ")
	> a$isdst

	[1] 1

	> b<-as.POSIXlt('2010-04-04 02:26:08',tz="NZ")
	> b$isdst

	[1] 0


So does R get its DST information from somewhere else? Any

suggestions

would be much appreciated!

Thanks

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