Date conversion with as.POSIXct and as.POSIXlt (PR#9196)
Note that there is some discussion in the help desk article in R News 4/1 and a table of tested conversions at the end of that article. If x is of class "Date" then for converting from Date to POSIXct the table suggests as.POSIXct(format(x)) or as.POSIXct(format(x), tz = "GMT") according to whether you want the current time zone or GMT.
On 9/1/06, erich.neuwirth at univie.ac.at <erich.neuwirth at univie.ac.at> wrote:
Full_Name: Erich Neuwirth Version: 2.3.1 OS: Windows XP, Linux Submission from: (NULL) (131.130.135.167) Converting Sys.Date() to a POSIX compliant time type in different ways produces inconsistent results:
Sys.date()
[1] "2006-09-01"
as.POSIXct(Sys.Date())
[1] "2006-09-01 02:00:00 CEST"
as.POSIXlt(Sys.Date())
[1] "2006-09-01"
as.POSIXct(as.POSIXlt(Sys.Date()))
[1] "2006-09-01 01:00:00 CEST" Applying as.POSIXct directly or first applying as.POSIXlt and then applying as.POSIXct produces different results. This happens on Linux with timezone "CEST"
Sys.time()
[1] "2006-09-01 11:03:36 CEST" and on Windows with timezone "W. Europe Daylight Time"
Sys.time()
[1] "2006-09-01 11:11:15 W. Europe Daylight Time"
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