[R] end of daylight saving time

[Denis Chabot]

Hi,

I read from the help on DateTimeClasses and various posts on this list  
that, quite logically, one needs to specify if DST is in function for  
the first hour  after the change from DST to ST in autumn.

Hence, in my time zone and on Mac OS X, I can do this:

a <- as.POSIXct("2008-11-02 01:30:00", tz="EST5EDT")  # to get  
automatic use of DST
b <- as.POSIXct("2008-11-02 01:30:00", tz="EST")  # to tell T this is  
the second occurrence of 1:30 that day, in ST
difftime(b,a)

But why can't I do this, to handle several date-times at once?

c <- rep("2008-11-02 01:30:00", 2)
tzone = c("EST5EDT", "EST")

as.POSIXct(c, tz=tzone)
Erreur dans strptime(xx, f <- "%Y-%m-%d %H:%M:%OS", tz = tz) :
   valeur 'tz' incorrecte

???

Thanks,

Denis Chabot

sessionInfo()
R version 2.9.1 Patched (2009-07-09 r48929)
x86_64-apple-darwin9.7.0

locale:
fr_CA.UTF-8/fr_CA.UTF-8/C/C/fr_CA.UTF-8/fr_CA.UTF-8

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

loaded via a namespace (and not attached):
[1] tools_2.9.1