[R] time zones from longitude, latitude, and date

[Gabor Grothendieck]

On Fri, Sep 20, 2013 at 4:31 PM, carlisle thacker
<carlisle.thacker at gmail.com> wrote:
> I was looking for something like shown on the map:
> http://upload.wikimedia.org/wikipedia/commons/8/88/World_Time_Zones_Map.png
>
> Information about local daylight savings times would also help.
>
> The data are from ships, supposedly in local time, but no time-zone info is
> given.  A function that would return time zone and whether or not daylight
> savings time applies at given date would would help.  I'm trying to track
> down more information about the data and whether they can be referenced to
> UTC.

The zone.tab file has this information.  See the Examples section at
the end of ?Sys.timezone for info on its whereabouts.