On Sep 5, 2013, at 5:07 AM, Paul Eggert <eggert@cs.ucla.edu> wrote:
kokosani kokosani wrote:
How for any coordinate determine the time zone?
There are some data for that, maintained elsewhere. Please see <http://www.iana.org/time-zones/repository/tz-link.html> and look for "Time zone boundaries".
The first of those: http://efele.net/maps/tz/ has shapefiles for tzdb zones. The second is claimed to "[contain] detailed lists of tz-related zone subdivision data", but I'm not sure where tzdb-related stuff is on that site. The others sound as if they handle "time zones" in the common sense of the word, rather than tzdb zones (a "time zone" may contain multiple tzdb zones if, for example, parts of a given time zone do time-shifting during part of the year and other parts don't). See also http://derickrethans.nl/what-time-is-it.html which has one person's way of answering "what tzdb zone contains this coordinate?" (involving sticking the tzdb shape files into MongoDB and using a MongoDB geometric operator).