Hi William, asking to the r-devel list I resolved the problem! It depends from the timezone (tz param) that I didn't specified and so R automatically uses my local time and considers also the daylight saving time (that comes at 2:00 at my position). As my dates are in solar time, I specified the time zone as "GMT" and it works! Here a simple example:
df = data.frame(DateTime = c( '2016-12-21 10:34:54', '2016-12-21 11:04:54', '2016-12-21 11:34:54', '2016-03-27 02:05:50', '2016-03-27 02:35:50', '2016-12-21 12:04:54', '2016-12-21 12:34:54' )) df$DateTime = as.POSIXlt(strptime(df$DateTime, format='%Y-%m-%d %H:%M:%S', tz='GMT')) ord = order(as.numeric(strptime(df$DateTime, format='%Y-%m-%d %H:%M:%S', tz='GMT'))) df.ord = df[ord,1] df.ord [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.