TZWhere

Lookup a time zone by latitude/longitude using the nearest neighbor method.

Caveats

The nearest neighbor method can sometimes be inacurrate, if compared to a point lookup in a polygon. In most cases, the risk of inaccuracy is acceptable.

Installation

Add this line to your application's Gemfile:

gem 'tzwhere'

And then execute:

$ bundle

Or install it yourself as:

$ gem install tzwhere

Usage

TZWhere.lookup(41.7599, -87.2079)

# => "America/Chicago"

Running Tests

Ensure the test dependencies are installed:

$ bundle

Run the test suite:

$ rake spec

DataSource

Uses the data available at http://download.geonames.org/export/dump/

The current version extract longitude, latitude and timezone from the cities5000 dataset. This set includes all citites with a population > 5000 (~47k entries).

Can be changes to either the cities1000(144k entires) or cities15000(23k entries) dataset by changing the update_points_data rake task and executing it. One will be faster the other one more accurate.

Contributing

See CONTRIBUTING.md

Copyright

Geocode data (points.dat) by Geonames.org is licensed under CC BY 3.0

See LICENSE for details.

alebruck/tzwhere