mapping location to a time zone

Question

I need to get the time zone for a given address/location. Assume that the address/location can be reverse geocoded (using google) to a lat/lng if necessary.

This means that I may not have a zip code.

I was really hoping that google provided some kind of API for this, but it seems that they don't. At a minimum you can google search for "time in washington, dc" and get the time/TZ -- but then I'd have to screen scrape that which is not fun :(

I know there are databases available that map locations to time zones, but that'd have to be maintained. Has anyone come up with a tricky solution to this problem?

Thanks!

score 4 · Answer 1 · answered Nov 12 '12 at 05:31

Google provides an API for this.

https://maps.googleapis.com/maps/api/timezone/<json or xml>?location=<lat>,<lng>&timestamp=<unix timestamp>&sensor=<true or false>

eg:

https://maps.googleapis.com/maps/api/timezone/json?location=39.6034810,-119.6822510&timestamp=1331161200&sensor=false

score 2 · Accepted Answer · answered Mar 13 '12 at 19:16

2

http://www.geonames.org/ provides an API that returns the timezone given a lat/lng

answered Mar 13 '12 at 19:16

jsharpe

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geonames isn't free, the 'demo' account which the samples use is limited to only 3000 requests/day. I was using it for dev purposes just now and it flat-out stopped working. – Dean Rather Nov 12 '12 at 04:20

score 0 · Answer 3 · answered Nov 17 '13 at 13:23

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I've written a small Java class to do this, with the data structure embedded in the code. If you want to avoid using a web service, and accuracy of 22km is good enough, and you're happy to assume that timezone boundaries don't change, then it could help.

https://sites.google.com/a/edval.biz/www/mapping-lat-lng-s-to-timezones

answered Nov 17 '13 at 13:23

Tim Cooper

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The more accurate version is 61484 line code. How is the performance of the code? – ProgrAmmar Sep 02 '14 at 06:32
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Performance is fast. It's just a binary search of lat's and long's. (Fast on any compiled language, but would be slow in PHP). – Tim Cooper Sep 03 '14 at 07:20

score 0 · Answer 4 · answered Oct 05 '10 at 21:21

The question needs to be clarified a bit more. What are you doing this for? What language(s) are you using? But how I would approach the problem is: First, create a table like structure that translates longitudes into zones(much like this table ). Next I would query the GMT either locally, or on the web somehow, and finally take the offset from the table and add it to GMT. This way there is no "maintenance" of the table since these longitudes don't change.

mapping location to a time zone

4 Answers4

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