Problem to convert date to number
On Apr 6, 2011, at 7:55 AM, Chris82 wrote:
Hi R users, I have a maybe small problem which I cannot solve by myself. I want to convert "chron" "dates" "times" (04/30/06 11:35:00)
Using the example from help(chron) > as.POSIXlt(x) # chron times are assumed to be UTC but are printed with the current local value [1] "1992-02-27 18:03:20 EST" "1992-02-27 17:29:56 EST" [3] "1992-01-13 20:03:30 EST" "1992-02-28 13:21:03 EST" [5] "1992-02-01 11:56:26 EST" > as.POSIXlt(x, tz="UTC") [1] "1992-02-27 23:03:20 UTC" "1992-02-27 22:29:56 UTC" [3] "1992-01-14 01:03:30 UTC" "1992-02-28 18:21:03 UTC" [5] "1992-02-01 16:56:26 UTC" > as.POSIXlt(x, tz="CEST") # "not working" [1] "1992-02-27 23:03:20 UTC" "1992-02-27 22:29:56 UTC" [3] "1992-01-14 01:03:30 UTC" "1992-02-28 18:21:03 UTC" [5] "1992-02-01 16:56:26 UTC" So it makes me wonder if as.POSIXct considers CEST to be a valid tz value. > as.POSIXlt(x, tz="XYZST") [1] "1992-02-27 23:03:20 UTC" "1992-02-27 22:29:56 UTC" [3] "1992-01-14 01:03:30 UTC" "1992-02-28 18:21:03 UTC" [5] "1992-02-01 16:56:26 UTC" > as.POSIXlt(x, tz="EST5EDT") # where I am, and seems to be working [1] "1992-02-27 18:03:20 EST" "1992-02-27 17:29:56 EST" [3] "1992-01-13 20:03:30 EST" "1992-02-28 13:21:03 EST" [5] "1992-02-01 11:56:26 EST" But despite the returned code from Sys.time() that TLA (EDT) does not "work": > Sys.time() [1] "2011-04-06 08:44:01 EDT" > as.POSIXlt(x, tz="EDT") # "EDT" printed as UTC values [1] "1992-02-27 23:03:20 UTC" "1992-02-27 22:29:56 UTC" [3] "1992-01-14 01:03:30 UTC" "1992-02-28 18:21:03 UTC" [5] "1992-02-01 16:56:26 UTC" But an unambiguous version does return the expected offset. All of this can be specific to your system (not provided) and your locale setting (also not provided) > as.POSIXlt(x, tz="UTC+02") [1] "1992-02-27 21:03:20 UTC" "1992-02-27 20:29:56 UTC" [3] "1992-01-13 23:03:30 UTC" "1992-02-28 16:21:03 UTC" [5] "1992-02-01 14:56:26 UTC"
David. > > > to a number with as.POSIXct. > > The Problem is that I can't choose different timezones. I always get > "CEST" > and not "UTC" what I need. > > date = as.POSIXct(y,tz="UTC") > > "2006-04-30 11:35:00 CEST" > Then I tried to use as.POSIXlt. > > date = as.POSIXlt(y,tz="UTC") > > "2006-04-30 11:35:00 UTC" > > The advantage is I get time in UTC but now the problem is that I can > calculate numbers. > > date <- as.double(date)/86400 > > it is not working with as.POSIXlt but with as.POSIXct > > > Thanks! > > With best regards > > > > -- > View this message in context: http://r.789695.n4.nabble.com/Problem-to-convert-date-to-number-tp3430571p3430571.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > R-help at 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. David Winsemius, MD West Hartford, CT