Country name for GPS coordinates

问题:

Is there an easy way to get the name of the country on whose territory a given point is located?

I don't care too much about accuracy nor about ambiguities given by political disputes. Just need a good enough approximation.

回答1:

EDIT: The Yahoo Where API is no longer available.

Try the Yahoo! APIs.

Latitude and Longitude

Latitude and longitude can be specified for the location parameter. Latitude and longitude may be expressed as decimal degrees or degrees-minutes-seconds, with either leading or trailing directionals or leading signs. If directionals are provided, longitude may appear before latitude. If directionals are not provided, longitude may appear before latitude if it is outside the range -90 to 90. Otherwise, the latitude must appear first. Punctuation marks (commas, degrees, minutes, seconds) are ignored.

Examples: 

•50.3 -120.5
•50.3, -120.5
•-120.5 50.3
•50.3 N 120.5 W
•120.5 W 50.3 N
•50 18 0 -120 30 0
•50 18 0 N 120 30 0 W
•50° 18' 0" N 120° 30' 0" W

The response element will give you the country, as well as many other elements.

Don't forget to send as parameter gflags=R, to make the reverse geocoding. If you want the output in json, send the parameter flags=J as well.

回答2:

Just for the reference, geonames.org also has a nice webservice, but it's rate limited (which was an issue in my case since I had to look up a big batch of coordinates).

Example: http://ws.geonames.org/findNearbyPlaceName?lat=47.3&lng=9

回答3:

How about using google's reverse geo-encoding service?

回答4:

Here's some JavaScript code to get the name of the country from latitude and longitude coordinates:

---

1. Using Google's geocoding services [jsfiddle]:

   var lookupCountryWithGoogle = function(lat, lng) { var latlng = new google.maps.LatLng(lat, lng);

   var geoCoder = new google.maps.Geocoder();
   
   geoCoder.geocode({
       location: latlng
   }, function(results, statusCode) {
       var lastResult = results.slice(-1)[0];
   
       if (statusCode == 'OK' && lastResult && 'address_components' in lastResult) {
           alert('coordinates: ' + lat + ', ' + lng + '\n' + 'country: ' + lastResult.address_components.slice(-1)[0].long_name);
       } else {
           alert('coordinates: ' + lat + ', ' + lng + '\n' + 'failed: ' + statusCode);
       }
   });
   

   };

   lookupCountryWithGoogle(43.7534932, 28.5743187); // will succeed lookupCountryWithGoogle(142, 124); // will fail

(You'll need to load Google's JavaScript support for this from a URL such as maps.google.com/maps/api/js?sensor=false&fake=.js)

---

1. Using ws.geonames.org [jsfiddle]:

   var lookupCountryWithGeonames = function(lat, lng) {

   $.getJSON('http://ws.geonames.org/countryCode', {
       lat: lat,
       lng: lng,
       type: 'JSON'
   }, function(results) {
       if (results.countryCode) {
           alert('coordinates: ' + lat + ', ' + lng + '\n' + 'country: ' + results.countryName);
       } else {
           alert('coordinates: ' + lat + ', ' + lng + '\n' + 'failed: ' + results.status.value + ' ' + results.status.message);
       }
   });
   

   };

   lookupCountryWithGeonames(43.7534932, 28.5743187); // will succeed

   lookupCountryWithGeonames(142, 124); // will fail ​

回答5:

You could also look at the services from tinygeocoder.

Another alternative is to download the country maps from natural earth (or another source). Using Geotools you could search whether the point is inside one of the countries.