[was " [R] end of daylight saving time"] Hi,
I got no reply with the previous subject line, probably a bad choice of subject on my part, so here it is again. I read from the help on DateTimeClasses and various posts on this list that, quite logically, one needs to specify if DST is active or not when time is between 1 and 2 AM on the first Sunday in November (for North America in recent years). This I can do for on date at a time: 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) Time difference of 1 hours But why can't I do the following, which appears to be a typical R way of doing things, 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 [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.