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How to get Timezone from latitude/longitude ?

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  How to get Timezone from latitude/longitude ? codetarsier@gmail.com - 2014-06-25 05:53 -0700
    Re: How to get Timezone from latitude/longitude ? Bernd Nawothnig <Bernd.Nawothnig@t-online.de> - 2014-06-25 15:09 +0200
    Re: How to get Timezone from latitude/longitude ? Larry Martell <larry.martell@gmail.com> - 2014-06-25 09:09 -0400
    Re: How to get Timezone from latitude/longitude ? Chris Angelico <rosuav@gmail.com> - 2014-06-25 23:27 +1000
      Re: How to get Timezone from latitude/longitude ? Marko Rauhamaa <marko@pacujo.net> - 2014-06-25 17:00 +0300
        Re: How to get Timezone from latitude/longitude ? Grant Edwards <invalid@invalid.invalid> - 2014-06-25 14:24 +0000
          Re: How to get Timezone from latitude/longitude ? Ethan Furman <ethan@stoneleaf.us> - 2014-06-25 07:34 -0700
            Re: How to get Timezone from latitude/longitude ? Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-06-26 11:29 +1200
              Re: How to get Timezone from latitude/longitude ? codetarsier@gmail.com - 2014-06-26 02:24 -0700
    Re: How to get Timezone from latitude/longitude ? Akira Li <4kir4.1i@gmail.com> - 2014-06-26 00:44 +0400

#73572 — How to get Timezone from latitude/longitude ?

Hi,

I'm looking for a python-library which can help me to get Timezone and Timezone-offset(UTC) from latitude/longitude. 

I'm not able to find an easy way to do it.

Thanks in advance. 

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#73573

On 2014-06-25, codetarsier@gmail.com wrote:
> I'm looking for a python-library which can help me to get Timezone and
> Timezone-offset(UTC) from latitude/longitude. 
>
> I'm not able to find an easy way to do it.

You can find the data as a zipped shapefile here:

http://efele.net/maps/tz/world/

Download the data and use pyshp and/or gdal/ogr for the lookup.

It may not be as simple as you wanted it to be, but it is possible.




Bernd

-- 
no time toulouse

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#73574

On Wed, Jun 25, 2014 at 8:53 AM,  <codetarsier@gmail.com> wrote:
> Hi,
>
> I'm looking for a python-library which can help me to get Timezone and Timezone-offset(UTC) from latitude/longitude.
>
> I'm not able to find an easy way to do it.
>
> Thanks in advance.

It took me 30 seconds on google to find this:

https://github.com/pegler/pytzwhere

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#73575

On Wed, Jun 25, 2014 at 10:53 PM,  <codetarsier@gmail.com> wrote:
> I'm looking for a python-library which can help me to get Timezone and Timezone-offset(UTC) from latitude/longitude.
>
> I'm not able to find an easy way to do it.

There isn't an easy way to do it.

At best, you would have to do a two-step lookup: first, figure out
what country and city you're in, based on lat/long; and then, look up
the appropriate timezone from the city. Unfortunately that won't
actually be perfect, because there are points on this planet's surface
that cannot be unambiguously assigned timezones... because timezones
are really messy.

Normally, the way to define timezones would be with the Olsen database
(tzdata), which defines "Australia/Melbourne" (where I live),
"America/Merida" (which is not a reimagining of "Brave" on a different
continent), "Africa/Libreville" (which presumably is where a popular
office suite came from), and so on. If you can get your users to pick
based on those, your work will be easy and unambiguous. Otherwise,
you're going to have a lot of work trying to recreate that...

Why do you need to work this out? Are you trying to use a user's IP
geolocation data to pick a timezone? Because that's doomed to failure.
Even if you have something like a phone's GPS fix, trying to guess the
timezone based on that is a bad idea. In fact, guessing is almost
always a bad idea.

On the other hand, if all you need is a rough approximation, just take
the longitude (positive if you're east of Greenwich, negative if
west), and multiply it by 24 hours/360° to get a theoretical timezone.
That's good enough for planting on a map, or for getting a rough idea
of whether it's morning, noon, evening, or night; most actual civil
timezones will be broadly near to that figure. (Some are a long way
away from it, though. New Zealand's Chatham Islands are at around
176.5°W, for a theoretical timezone of roughly UTC-11:45, but the
actual timezone is UTC+12:45, almost but not exactly an entire day
ahead of where you might think.) Of course, that ignores every civil
invention, including the abomination of DST, but that might be
considered an advantage rather than a flaw...

ChrisA

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#73576

Chris Angelico <rosuav@gmail.com>:

> Are you trying to use a user's IP geolocation data to pick a timezone?
> Because that's doomed to failure.

Some years back my employer switched ISPs in Southern California. The
following morning Google displayed everything in Hebrew. It took a week
or two to be corrected.


Marko

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#73577

On 2014-06-25, Marko Rauhamaa <marko@pacujo.net> wrote:
> Chris Angelico <rosuav@gmail.com>:
>
>> Are you trying to use a user's IP geolocation data to pick a timezone?
>> Because that's doomed to failure.
>
> Some years back my employer switched ISPs in Southern California. The
> following morning Google displayed everything in Hebrew. It took a week
> or two to be corrected.

Learning Hebrew in a week or two is a pretty impressive feat.

-- 
Grant Edwards               grant.b.edwards        Yow! ... I want to perform
                                  at               cranial activities with
                              gmail.com            Tuesday Weld!!

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#73579

On 06/25/2014 07:24 AM, Grant Edwards wrote:
> On 2014-06-25, Marko Rauhamaa wrote:
>>
>> Some years back my employer switched ISPs in Southern California. The
>> following morning Google displayed everything in Hebrew. It took a week
>> or two to be corrected.
>
> Learning Hebrew in a week or two is a pretty impressive feat.

Maybe he learned using one of those language classes I keep hearing about in my email...

--
~Ethan~

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#73596

Ethan Furman wrote:
> On 06/25/2014 07:24 AM, Grant Edwards wrote:
> 
>> On 2014-06-25, Marko Rauhamaa wrote:
>>
>>> Some years back my employer switched ISPs in Southern California. The
>>> following morning Google displayed everything in Hebrew. It took a week
>>> or two to be corrected.
>>
>> Learning Hebrew in a week or two is a pretty impressive feat.
> 
> Maybe he learned using one of those language classes I keep hearing 
> about in my email...

Nah, the solution's obvious -- just use Google Translate
to turn it back into English.

-- 
Greg

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#73611

Thanks for the help people.
I was looking for the Malyasia City(lat/long)timezones.

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#73589

Larry Martell <larry.martell@gmail.com> writes:

> On Wed, Jun 25, 2014 at 8:53 AM,  <codetarsier@gmail.com> wrote:
>> Hi,
>>
>> I'm looking for a python-library which can help me to get Timezone
>> and Timezone-offset(UTC) from latitude/longitude.
>>
>> I'm not able to find an easy way to do it.
>>
>> Thanks in advance.
>
> It took me 30 seconds on google to find this:
>
> https://github.com/pegler/pytzwhere

Note: tzwhere may consume 750GB memory doing nothing
https://github.com/pegler/pytzwhere/pull/10

You could generate a postgis timezone database from efele.net/tz map or
use an online service instead http://stackoverflow.com/a/16519004


--
akira

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