I am in a different time zone, EDT, on Windows XP and can't replicate this but you might try reading the latest R News article on dates and times for some ideas, viz. page 32 of:
http://cran.r-project.org/doc/Rnews/Rnews_2004-1.pd In particular, try converting them to chron and then doing your manipulations in chron or else convert them from chron to POSIXct: require(chron) r.asc <- raincida$ts r.chron <- chron(substring(r.asc, 1, 10), substring(r.asc, 12, 19), format = c("d/m/y", "h:m:s")) r.ct <- as.POSIXct(r.chron) format(r.ct, tz="GMT") # display POSIXct in GMT Date: Tue, 17 Aug 2004 16:25:12 +0200 From: javier garcia - CEBAS <[EMAIL PROTECTED]> To: Prof Brian Ripley <[EMAIL PROTECTED]>, <[EMAIL PROTECTED]> Subject: [R] Fwd: strptime() problem? Hi all; I've already send a similar e-mail to the list and Prof. Brian Ripley answered me but my doubts remain unresolved. Thanks for the clarification, but perhaps I wasn't clear enough in posting my questions. I've got a postgres database which I read into R. The first column is Timestamp with timezone, and my data are already in UTC format. An 'printed' extract of R character column, resulting from the timestamptz field is: raincida$ts: [2039] "25/03/2000 22:00:00 UTC" "25/03/2000 23:00:00 UTC" [2041] "26/03/2000 00:00:00 UTC" "26/03/2000 01:00:00 UTC" [2043] "26/03/2000 02:00:00 UTC" "26/03/2000 03:00:00 UTC" [2045] "26/03/2000 04:00:00 UTC" "26/03/2000 05:00:00 UTC" #And I need to convert this character column into POSIXct, for eventual work. #As I can see in the documentation, the process is to use strptime(), what #creates an object POSIXlt and doesn't allow to specify that the time zone of #the data is already UTC; followed by as.POSIXct() > lluvia.strptime <- strptime(raincida$ts, format="%d/%m/%Y %H:%M:%S") > lluvia.strptime.POSIXct <- as.POSIXct(lluvia.strptime,tz="GMT") A "printed" extract is: [2039] "2000-03-25 22:00:00 GMT" "2000-03-25 23:00:00 GMT" [2041] "2000-03-26 00:00:00 GMT" "2000-03-26 01:00:00 GMT" [2043] "2000-03-26 03:00:00 GMT" "2000-03-26 03:00:00 GMT" [2045] "2000-03-26 04:00:00 GMT" "2000-03-26 05:00:00 GMT" As we can see, elements [2043] differ. Shouldn't they be similar as the rest of the other shown elements? I thought this was a bug, but it seems that I've got and conceptual error.(?). This happens several times in my data, and produces eventual errors. Please, how could I resolved this? Thanks all, and best regards, Javier G. ______________________________________________ [EMAIL PROTECTED] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html