I believe the lubridate package does a good job with time zones.
> install.packages("lubridate")
> library(lubridate)
Look at the supplied functions with_tz() and force_tz().
HTH,
Bill.
William J. Michels, Ph.D.
On Fri, Apr 7, 2017 at 12:52 AM, Jeff Newmiller
<jdnew...@dcn.davis.ca.us> wrote:
> R does a poor job of supporting timezone-specific objects... you have to
> transfer the necessary attributes explicitly for many operations. (It does
> no job of supporting element-specific timezones so don't go there.)
>
> The good news is that R is pretty good at working with points in time, since
> the default behavior of implementing time with numeric values in GMT always
> means you can specify whatever timezone you want input or output to use, and
> the timestamps are always ordered correctly in time.
>
> I find that using the default empty string for tz attributes on POSIXt
> objects (meaning use whatever is default) and letting the TZ environment
> variable control the "current default" timezone is the most effective way to
> avoid frustration with this. Don't hesitate to change that variable when you
> need to convert to or from character or POSIXlt..
>
> Sys.setenv( TZ="Etc/GMT+5" ) # read ?Olson
> x <- as.POSIXct( "2017-03-31 19:00:00" )
> Sys.setenv( TZ="Etc/GMT+8" )
> y <- as.POSIXct( "2017-03-31 16:00:00" )
> Sys.setenv( TZ="GMT" )
> print( x )
> print( y )
> --
> Sent from my phone. Please excuse my brevity.
>
> On April 7, 2017 12:00:52 AM PDT, Troels Ring <tr...@gvdnet.dk> wrote:
>>Thanks a lot - perhaps it is just understanding how times dates are
>>handled, sorry to bother if that is just the case
>>
>>C[1]==A[1] # TRUE
>>
>>but
>>
>>C[1]
>>[1] "2013-03-28 07:00:00 CET"
>>A[1]
>>[1] "2013-03-28 06:00:00 UTC"
>>
>>
>>
>>
>>
>>Den 07-04-2017 kl. 08:27 skrev Ulrik Stervbo:
>>> Hi Troels,
>>>
>>> I get no error. I think we need more information to be of any help.
>>>
>>> Best wishes,
>>> Ulrik
>>>
>>> On Fri, 7 Apr 2017 at 08:17 Troels Ring <tr...@gvdnet.dk> wrote:
>>>
>>>> Dear friends - I have further problems handling dates_times, as
>>>> demonstrated below where concatenating two formatted vectors of
>>>> date_times results in errors.
>>>> I wonder why this happens and what was wrong in trying to take these
>>two
>>>> vectors together
>>>> All best wishes
>>>> Troels Ring
>>>> Aalborg, Denmark
>>>> Windows
>>>> R version 3.3.2 (2016-10-31)
>>>>
>>>>
>>>> A <- structure(c(1364450400, 1364450400, 1364536800, 1364623200,
>>>> 1364709600,
>>>> 1364796000, 1364882400, 1364968800, 1365055200, 1365141600,
>>1365228000,
>>>> 1365314400, 1365400800), class = c("POSIXct", "POSIXt"), tzone =
>>"UTC")
>>>> A
>>>> B <- structure(c(1365141600, 1365228000, 1365314400, 1365400800,
>>>> 1365487200,
>>>> 1365573600, 1365660000, 1365746400, 1365832800, 1365919200,
>>1366005600,
>>>> 1366092000), class = c("POSIXct", "POSIXt"), tzone = "UTC")
>>>> B
>>>> C <- c(A,B)
>>>> C
>>>>
>>>> ______________________________________________
>>>> 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.
>>>>
>>> [[alternative HTML version deleted]]
>>>
>>> ______________________________________________
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>>> PLEASE do read the posting guide
>>http://www.R-project.org/posting-guide.html
>>> and provide commented, minimal, self-contained, reproducible code.
>>>
>>
>>______________________________________________
>>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.
>
> ______________________________________________
> 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.
______________________________________________
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