Comment obtenir un fuseau horaire à partir d'un lieu en utilisant les coordonnées de latitude et de longitude?

Que Diriez-vous de cette solution pour le noeud.js https://github.com/mattbornski/tzwhere

et son pendant Python: https://github.com/pegler/pytzwhere

Nous Téléporter juste commencé l'ouverture de notre API et l'un des usecases est d'exposer TZ information pour les coordonnées.

par exemple, on pourrait demander toutes nos Informations TZ disponibles pour les coordonnées de la manière suivante:

curl -s https://api.teleport.org/api/locations/59.4372,24.7453/?embed=location:nearest-cities/location:nearest-city/city:timezone/tz:offsets-now | jq '._embedded."location:nearest-cities"[0]._embedded."location:nearest-city"._embedded."city:timezone"'

ce serait retourner le suivant

{
  "_embedded": {
    "tz:offsets-now": {
      "_links": {
        "self": {
          "href": "https://api.teleport.org/api/timezones/iana:Europe%2FTallinn/offsets/?date=2015-09-07T11%3A20%3A09Z"
        }
      },
      "base_offset_min": 120,
      "dst_offset_min": 60,
      "end_time": "2015-10-25T01:00:00Z",
      "short_name": "EEST",
      "total_offset_min": 180,
      "transition_time": "2015-03-29T01:00:00Z"
    }
  },
  "_links": {
    "self": {
      "href": "https://api.teleport.org/api/timezones/iana:Europe%2FTallinn/"
    },
    "tz:offsets": {
      "href": "https://api.teleport.org/api/timezones/iana:Europe%2FTallinn/offsets/{?date}",
      "templated": true
    },
    "tz:offsets-now": {
      "href": "https://api.teleport.org/api/timezones/iana:Europe%2FTallinn/offsets/?date=2015-09-07T11%3A20%3A09Z"
    }
  },
  "iana_name": "Europe/Tallinn"
}

Pour l'exemple j'ai utilisé ./jq pour JSON parsing.

vous pouvez utiliser geolocator.js pour obtenir facilement le fuseau horaire et plus...

il utilise Google APIs qui nécessitent une clé. Donc, d'abord vous configurez geolocator:

geolocator.config({
    language: "en",
    google: {
        version: "3",
        key: "YOUR-GOOGLE-API-KEY"
    }
});

obtenez le fuseau horaire si vous avez les coordonnées:

geolocator.getTimeZone(options, function (err, timezone) {
    console.log(err || timezone);
});

exemple de sortie:

{
    id: "Europe/Paris",
    name: "Central European Standard Time",
    abbr: "CEST",
    dstOffset: 0,
    rawOffset: 3600,
    timestamp: 1455733120
}

Localisez puis obtenez le fuseau horaire et plus

si vous n'avez pas les coordonnées, vous pouvez d'abord localiser la position de l'utilisateur.

exemple ci-dessous va d'abord essayer L'API de géolocalisation HTML5 pour obtenir les coordonnées. Si elle échoue ou est rejetée, elle obtiendra les coordonnées via la recherche géo-IP. Enfin, il obtiendra le fuseau horaire et plus...

var options = {
    enableHighAccuracy: true,
    timeout: 6000,
    maximumAge: 0,
    desiredAccuracy: 30,
    fallbackToIP: true, // if HTML5 fails or rejected
    addressLookup: true, // this will get full address information
    timezone: true,
    map: "my-map" // this will even create a map for you
};
geolocator.locate(options, function (err, location) {
    console.log(err || location);
});

exemple de sortie:

{
    coords: {
        latitude: 37.4224764,
        longitude: -122.0842499,
        accuracy: 30,
        altitude: null,
        altitudeAccuracy: null,
        heading: null,
        speed: null
    },
    address: {
        commonName: "",
        street: "Amphitheatre Pkwy",
        route: "Amphitheatre Pkwy",
        streetNumber: "1600",
        neighborhood: "",
        town: "",
        city: "Mountain View",
        region: "Santa Clara County",
        state: "California",
        stateCode: "CA",
        postalCode: "94043",
        country: "United States",
        countryCode: "US"
    },
    formattedAddress: "1600 Amphitheatre Parkway, Mountain View, CA 94043, USA",
    type: "ROOFTOP",
    placeId: "ChIJ2eUgeAK6j4ARbn5u_wAGqWA",
    timezone: {
        id: "America/Los_Angeles",
        name: "Pacific Standard Time",
        abbr: "PST",
        dstOffset: 0,
        rawOffset: -28800
    },
    flag: "//cdnjs.cloudflare.com/ajax/libs/flag-icon-css/2.3.1/flags/4x3/us.svg",
    map: {
        element: HTMLElement,
        instance: Object, // google.maps.Map
        marker: Object, // google.maps.Marker
        infoWindow: Object, // google.maps.InfoWindow
        options: Object // map options
    },
    timestamp: 1456795956380
}

Voici comment vous pouvez utiliser l'éditeur de script de Google pour obtenir le nom et le timeZoneId de timezon à l'intérieur d'une gsheet.

Étape 1. Obtenir une clé API de Google fuseau horaire de l'API

Étape 2. Créer une nouvelle gsheet. Sous le menu "outils" cliquez sur "script editor". Ajouter le code suivant:

function getTimezone(lat, long) {  
  var apiKey = 'INSERTAPIKEYHERE'
  var url = 'https://maps.googleapis.com/maps/api/timezone/json?location=' + lat + ',' + long + '&timestamp=1331161200&key=' + apiKey 
  var response = UrlFetchApp.fetch(url);
  var data = JSON.parse(response.getContentText());
  return data["timeZoneName"];
}

Étape 3. Enregistrer et publier votre getTimezone() fonction et l'utiliser comme indiqué dans l'image ci-dessus.

Ok voici la version courte sans heure NTP correcte:

String get_xml_server_reponse(String server_url){

URL xml_server = null;

String xmltext = "";

InputStream input;


try {
    xml_server = new URL(server_url);


    try {
        input = xml_server.openConnection().getInputStream();


        final BufferedReader reader = new BufferedReader(new InputStreamReader(input));
        final StringBuilder sBuf = new StringBuilder();

        String line = null;
        try {
            while ((line = reader.readLine()) != null) 
            {
                sBuf.append(line);
            }
           } 
        catch (IOException e) 
          {
                Log.e(e.getMessage(), "XML parser, stream2string 1");
          } 
        finally {
            try {
                input.close();
                }
            catch (IOException e) 
            {
                Log.e(e.getMessage(), "XML parser, stream2string 2");
            }
        }

        xmltext =  sBuf.toString();

    } catch (IOException e1) {

            e1.printStackTrace();
        }


    } catch (MalformedURLException e1) {

      e1.printStackTrace();
    }

 return  xmltext;

} 


long get_time_zone_time_l(GeoPoint gp){


        String raw_offset = "";
        String dst_offset = "";

        double Longitude = gp.getLongitudeE6()/1E6;
        double Latitude = gp.getLatitudeE6()/1E6;

        long tsLong = System.currentTimeMillis()/1000;


        if (tsLong != 0)
        {

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

        String request = "https://maps.googleapis.com/maps/api/timezone/xml?location="+Latitude+","+ Longitude+ "&timestamp="+tsLong +"&sensor=false";

        String xmltext = get_xml_server_reponse(request);

        if(xmltext.compareTo("")!= 0)
        {

         int startpos = xmltext.indexOf("<TimeZoneResponse");
         xmltext = xmltext.substring(startpos);



        XmlPullParser parser;
        try {
            parser = XmlPullParserFactory.newInstance().newPullParser();


             parser.setInput(new StringReader (xmltext));

             int eventType = parser.getEventType();  

             String tagName = "";


             while(eventType != XmlPullParser.END_DOCUMENT) {
                 switch(eventType) {

                     case XmlPullParser.START_TAG:

                           tagName = parser.getName();

                         break;


                     case XmlPullParser.TEXT :


                        if  (tagName.equalsIgnoreCase("raw_offset"))
                          if(raw_offset.compareTo("")== 0)                               
                            raw_offset = parser.getText();  

                        if  (tagName.equalsIgnoreCase("dst_offset"))
                          if(dst_offset.compareTo("")== 0)
                            dst_offset = parser.getText();  


                        break;   

                 }

                 try {
                        eventType = parser.next();
                    } catch (IOException e) {

                        e.printStackTrace();
                    }

                }

                } catch (XmlPullParserException e) {

                    e.printStackTrace();
                    erg += e.toString();
                }

        }      

        int ro = 0;
        if(raw_offset.compareTo("")!= 0)
        { 
            float rof = str_to_float(raw_offset);
            ro = (int)rof;
        }

        int dof = 0;
        if(dst_offset.compareTo("")!= 0)
        { 
            float doff = str_to_float(dst_offset);
            dof = (int)doff;
        }

        tsLong = (tsLong + ro + dof) * 1000;


        }


  return tsLong;

}

et l'utiliser avec:

GeoPoint gp = new GeoPoint(39.6034810,-119.6822510);
long Current_TimeZone_Time_l = get_time_zone_time_l(gp);

si vous voulez utiliser geonames.org alors utilise ce code. (Mais geonames.org est très lent parfois)

String get_time_zone_time_geonames(GeoPoint gp){


        String erg = "";

        double Longitude = gp.getLongitudeE6()/1E6;
        double Latitude = gp.getLatitudeE6()/1E6;



        String request = "http://ws.geonames.org/timezone?lat="+Latitude+"&lng="+ Longitude+ "&style=full";

        URL time_zone_time = null;

        InputStream input;
       // final StringBuilder sBuf = new StringBuilder();


        try {
            time_zone_time = new URL(request);


        try {
            input = time_zone_time.openConnection().getInputStream();


        final BufferedReader reader = new BufferedReader(new InputStreamReader(input));
            final StringBuilder sBuf = new StringBuilder();

            String line = null;
            try {
                while ((line = reader.readLine()) != null) {
                    sBuf.append(line);
                }
            } catch (IOException e) {
                    Log.e(e.getMessage(), "XML parser, stream2string 1");
            } finally {
                try {
                    input.close();
                } catch (IOException e) {
                    Log.e(e.getMessage(), "XML parser, stream2string 2");
                }
            }




             String xmltext = sBuf.toString();


             int startpos = xmltext.indexOf("<geonames");
             xmltext = xmltext.substring(startpos);



            XmlPullParser parser;
            try {
                parser = XmlPullParserFactory.newInstance().newPullParser();


            parser.setInput(new StringReader (xmltext));

            int eventType = parser.getEventType();  

            String tagName = "";

            while(eventType != XmlPullParser.END_DOCUMENT) {
                switch(eventType) {

                    case XmlPullParser.START_TAG:

                          tagName = parser.getName();

                        break;


                    case XmlPullParser.TEXT :


                        if  (tagName.equalsIgnoreCase("time"))
                          erg = parser.getText();  


                    break;   

                }

                try {
                    eventType = parser.next();
                } catch (IOException e) {

                    e.printStackTrace();
                }

            }

            } catch (XmlPullParserException e) {

                e.printStackTrace();
                erg += e.toString();
            }



            } catch (IOException e1) {

                e1.printStackTrace();
            }


            } catch (MalformedURLException e1) {

                e1.printStackTrace();
            }





        return erg;

 }

et l'utiliser avec:

GeoPoint gp = new GeoPoint(39.6034810,-119.6822510);
String Current_TimeZone_Time = get_time_zone_time_geonames(gp);

en utilisant la latitude et la longitude obtenir le fuseau horaire de l'emplacement actuel ci-dessous code travaillé pour moi

String data = null;         
LocationManager locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);
Location ll = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
double lat = 0,lng = 0;
if(ll!=null){
    lat=ll.getLatitude();
    lng=ll.getLongitude();
}
System.out.println(" Last known location of device  == "+lat+"    "+lng);

InputStream iStream = null; 
HttpURLConnection urlConnection = null;
try{
    timezoneurl = timezoneurl+"location=22.7260783,75.8781553&timestamp=1331161200";   //&key=AIzaSyDZMS5Za6yG_66gAK8PL_KH1ZSS9NbWC";                   
    // timezoneurl = timezoneurl+"location="+lat+","+lng+"&timestamp=1331161200";//&key=AIzaSyDZMS5Za6yG_66gAK8PL_KH1ZSS9NbWCbg";

    URL url = new URL(timezoneurl);                
    // Creating an http connection to communicate with url 
    urlConnection = (HttpURLConnection) url.openConnection(); 

    // Connecting to url 
    urlConnection.connect();                

    // Reading data from url 
    iStream = urlConnection.getInputStream();

    BufferedReader br = new BufferedReader(new InputStreamReader(iStream));

    StringBuffer sb  = new StringBuffer();
    String line = "";
    while( ( line = br.readLine())  != null){
        sb.append(line);
    }
    data = sb.toString();
    br.close();

}catch(Exception e){
    Log.d("Exception while downloading url", e.toString());
}finally{
    try {
        iStream.close();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    urlConnection.disconnect();
}

try {
    if(data!=null){
        JSONObject jobj=new JSONObject(data);
        timezoneId = jobj.getString("timeZoneId");

        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
        format.setTimeZone(TimeZone.getTimeZone(timezoneId));

        Calendar cl = Calendar.getInstance(TimeZone.getTimeZone(timezoneId));
        System.out.println("time zone id in android ==  "+timezoneId);

        System.out.println("time zone of  device in android == "+TimeZone.getTimeZone(timezoneId));
        System.out.println("time fo device in android "+cl.getTime());
    }
} catch (Exception e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}

il est en effet important de reconnaître que c'est un problème plus compliqué que la plupart des gens le soupçonneraient. En pratique, bon nombre d'entre nous sommes également disposés à accepter un code de travail qui fonctionne pour "le plus grand nombre possible de cas", où au moins ses problèmes mortels peuvent être identifiés et minimisés collectivement. Donc je poste ceci avec tout cela et l'esprit de L'OP en tête. Enfin, pour une valeur pratique à d'autres qui tentent de convertir GPS en fuseau horaire avec l'objectif final d'avoir un objet temporel sensible à la localisation (et plus important encore pour aider à améliorer la qualité des implémentations moyennes avec les objets temporels qui suivent ce wiki) voici ce que j'ai généré en Python (s'il vous plaît n'hésitez pas à éditer):

import pytz
from datetime import datetime
from tzwhere import tzwhere

def timezoned_unixtime(latitude, longitude, dt):
    tzw = tzwhere.tzwhere()
    timezone_str = tzw.tzNameAt(latitude, longitude)
    timezone = pytz.timezone(timezone_str)
    timezone_aware_datetime = timezone.localize(dt, is_dst=None)
    unix_time = (timezone_aware_datetime - datetime(1970, 1, 1, tzinfo=pytz.utc)).total_seconds()
    return unix_time

dt = datetime(year=2017, month=1, day=17, hour=12, minute=0, second=0)
print timezoned_unixtime(latitude=40.747854, longitude=-74.004733, dt=dt)

1. il y a plusieurs sources en ligne qui ont des données geojson pour les fuseaux horaires ( en voici une , en voilà une une autre

2. utilisez une bibliothèque de géométrie pour créer des objets polygones à partir des coordonnées de geojson ( shapely [python], GEOS [c++], JTS [java], NTS [.net]).

3. Convertissez votre lat/lng en objet point (cependant votre bibliothèque représente cela) et vérifiez si elle croise le polygone timezone.

   from shapely.geometry import Polygon, Point
   
   def get_tz_from_lat_lng(lat, lng):
       for tz, geojson in timezones.iteritems():
           coordinates = geojson['features'][0]['geometry']['coordinates']
           polygon = Polygon(coordinates)
           point = Point(lng, lat)
           if polygon.contains(point):
               return tz
   

essayez ce code pour utiliser L'API Google Time Zone de Java avec le Client NTP actuel Time et corriger utc_datetime_from_timestamp convertir:

String get_xml_server_reponse(String server_url){

    URL xml_server = null;

    String xmltext = "";

    InputStream input;


    try {
        xml_server = new URL(server_url);


        try {
            input = xml_server.openConnection().getInputStream();


            final BufferedReader reader = new BufferedReader(new InputStreamReader(input));
            final StringBuilder sBuf = new StringBuilder();

            String line = null;
            try {
                while ((line = reader.readLine()) != null) 
                {
                    sBuf.append(line);
                }
               } 
            catch (IOException e) 
              {
                    Log.e(e.getMessage(), "XML parser, stream2string 1");
              } 
            finally {
                try {
                    input.close();
                    }
                catch (IOException e) 
                {
                    Log.e(e.getMessage(), "XML parser, stream2string 2");
                }
            }

            xmltext =  sBuf.toString();

        } catch (IOException e1) {

                e1.printStackTrace();
            }


        } catch (MalformedURLException e1) {

          e1.printStackTrace();
        }

     return  xmltext;

  }     


 private String get_UTC_Datetime_from_timestamp(long timeStamp){

    try{

        Calendar cal = Calendar.getInstance();
        TimeZone tz = cal.getTimeZone();

        int tzt = tz.getOffset(System.currentTimeMillis());

        timeStamp -= tzt;

        // DateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss",Locale.getDefault());
        DateFormat sdf = new SimpleDateFormat();
        Date netDate = (new Date(timeStamp));
        return sdf.format(netDate);
    }
    catch(Exception ex){
        return "";
     }
    } 

 class NTP_UTC_Time
 {
     private static final String TAG = "SntpClient";

     private static final int RECEIVE_TIME_OFFSET = 32;
     private static final int TRANSMIT_TIME_OFFSET = 40;
     private static final int NTP_PACKET_SIZE = 48;

     private static final int NTP_PORT = 123;
     private static final int NTP_MODE_CLIENT = 3;
     private static final int NTP_VERSION = 3;

     // Number of seconds between Jan 1, 1900 and Jan 1, 1970
     // 70 years plus 17 leap days
     private static final long OFFSET_1900_TO_1970 = ((365L * 70L) + 17L) * 24L * 60L * 60L;

     private long mNtpTime;

     public boolean requestTime(String host, int timeout) {
         try {
             DatagramSocket socket = new DatagramSocket();
             socket.setSoTimeout(timeout);
             InetAddress address = InetAddress.getByName(host);
             byte[] buffer = new byte[NTP_PACKET_SIZE];
             DatagramPacket request = new DatagramPacket(buffer, buffer.length, address, NTP_PORT);

             buffer[0] = NTP_MODE_CLIENT | (NTP_VERSION << 3);

             writeTimeStamp(buffer, TRANSMIT_TIME_OFFSET);

             socket.send(request);

             // read the response
             DatagramPacket response = new DatagramPacket(buffer, buffer.length);
             socket.receive(response);          
             socket.close();

             mNtpTime = readTimeStamp(buffer, RECEIVE_TIME_OFFSET);            
         } catch (Exception e) {
           //  if (Config.LOGD) Log.d(TAG, "request time failed: " + e);
             return false;
         }

         return true;
     }


     public long getNtpTime() {
         return mNtpTime;
     }


     /**
      * Reads an unsigned 32 bit big endian number from the given offset in the buffer.
      */
     private long read32(byte[] buffer, int offset) {
         byte b0 = buffer[offset];
         byte b1 = buffer[offset+1];
         byte b2 = buffer[offset+2];
         byte b3 = buffer[offset+3];

         // convert signed bytes to unsigned values
         int i0 = ((b0 & 0x80) == 0x80 ? (b0 & 0x7F) + 0x80 : b0);
         int i1 = ((b1 & 0x80) == 0x80 ? (b1 & 0x7F) + 0x80 : b1);
         int i2 = ((b2 & 0x80) == 0x80 ? (b2 & 0x7F) + 0x80 : b2);
         int i3 = ((b3 & 0x80) == 0x80 ? (b3 & 0x7F) + 0x80 : b3);

         return ((long)i0 << 24) + ((long)i1 << 16) + ((long)i2 << 8) + (long)i3;
     }

     /**
      * Reads the NTP time stamp at the given offset in the buffer and returns 
      * it as a system time (milliseconds since January 1, 1970).
      */    
     private long readTimeStamp(byte[] buffer, int offset) {
         long seconds = read32(buffer, offset);
         long fraction = read32(buffer, offset + 4);
         return ((seconds - OFFSET_1900_TO_1970) * 1000) + ((fraction * 1000L) / 0x100000000L);        
     }

     /**
      * Writes 0 as NTP starttime stamp in the buffer. --> Then NTP returns Time OFFSET since 1900
      */    
     private void writeTimeStamp(byte[] buffer, int offset) {        
         int ofs =  offset++;

         for (int i=ofs;i<(ofs+8);i++)
           buffer[i] = (byte)(0);             
     }

 }

 String get_time_zone_time(GeoPoint gp){

        String erg = "";
        String raw_offset = "";
        String dst_offset = "";

        double Longitude = gp.getLongitudeE6()/1E6;
        double Latitude = gp.getLatitudeE6()/1E6;



        long tsLong = 0; // System.currentTimeMillis()/1000;

        NTP_UTC_Time client = new NTP_UTC_Time();

        if (client.requestTime("pool.ntp.org", 2000)) {              
          tsLong = client.getNtpTime();
        }

        if (tsLong != 0)
        {

        tsLong = tsLong  / 1000;

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

        String request = "https://maps.googleapis.com/maps/api/timezone/xml?location="+Latitude+","+ Longitude+ "&timestamp="+tsLong +"&sensor=false";

        String xmltext = get_xml_server_reponse(request);

        if(xmltext.compareTo("")!= 0)
        {

         int startpos = xmltext.indexOf("<TimeZoneResponse");
         xmltext = xmltext.substring(startpos);



        XmlPullParser parser;
        try {
            parser = XmlPullParserFactory.newInstance().newPullParser();


             parser.setInput(new StringReader (xmltext));

             int eventType = parser.getEventType();  

             String tagName = "";


             while(eventType != XmlPullParser.END_DOCUMENT) {
                 switch(eventType) {

                     case XmlPullParser.START_TAG:

                           tagName = parser.getName();

                         break;


                     case XmlPullParser.TEXT :


                        if  (tagName.equalsIgnoreCase("raw_offset"))
                          if(raw_offset.compareTo("")== 0)                               
                            raw_offset = parser.getText();  

                        if  (tagName.equalsIgnoreCase("dst_offset"))
                          if(dst_offset.compareTo("")== 0)
                            dst_offset = parser.getText();  


                        break;   

                 }

                 try {
                        eventType = parser.next();
                    } catch (IOException e) {

                        e.printStackTrace();
                    }

                }

                } catch (XmlPullParserException e) {

                    e.printStackTrace();
                    erg += e.toString();
                }

        }      

        int ro = 0;
        if(raw_offset.compareTo("")!= 0)
        { 
            float rof = str_to_float(raw_offset);
            ro = (int)rof;
        }

        int dof = 0;
        if(dst_offset.compareTo("")!= 0)
        { 
            float doff = str_to_float(dst_offset);
            dof = (int)doff;
        }

        tsLong = (tsLong + ro + dof) * 1000;



        erg = get_UTC_Datetime_from_timestamp(tsLong);
        }


  return erg;

}

et l'utiliser avec:

GeoPoint gp = new GeoPoint(39.6034810,-119.6822510);
String Current_TimeZone_Time = get_time_zone_time(gp);

https://en.wikipedia.org/wiki/Great-circle_distance

et voici une bonne implémentation en utilisant les données JSON: https://github.com/agap/llttz

public TimeZone nearestTimeZone(Location node) {
    double bestDistance = Double.MAX_VALUE;
    Location bestGuess = timeZones.get(0);

    for (Location current : timeZones.subList(1, timeZones.size())) {
        double newDistance = distanceInKilometers(node, current);

        if (newDistance < bestDistance) {
            bestDistance = newDistance;
            bestGuess = current;
        }
    }

    return java.util.TimeZone.getTimeZone(bestGuess.getZone());
}

  protected double distanceInKilometers(final double latFrom, final double lonFrom, final double latTo, final double lonTo) {
        final double meridianLength = 111.1;
        return meridianLength * centralAngle(latFrom, lonFrom, latTo, lonTo);
    }

    protected double centralAngle(final Location from, final Location to) {
        return centralAngle(from.getLatitude(), from.getLongitude(), to.getLatitude(), to.getLongitude());
    }

    protected double centralAngle(final double latFrom, final double lonFrom, final double latTo, final double lonTo) {
        final double latFromRad = toRadians(latFrom),
                lonFromRad = toRadians(lonFrom),
                latToRad   = toRadians(latTo),
                lonToRad   = toRadians(lonTo);

        final double centralAngle = toDegrees(acos(sin(latFromRad) * sin(latToRad) + cos(latFromRad) * cos(latToRad) * cos(lonToRad - lonFromRad)));

        return centralAngle <= 180.0 ? centralAngle : (360.0 - centralAngle);
    }

    protected double distanceInKilometers(final Location from, final Location to) {
        return distanceInKilometers(from.getLatitude(), from.getLongitude(), to.getLatitude(), to.getLongitude());
    }
}

De Guppy:

import geocoders
g = geocoders.GoogleV3()
place, (lat, lng) = g.geocode('Fairbanks')
print place, (lat, lng)
Fairbanks, AK, USA (64.8377778, -147.7163889)
timezone = g.timezone((lat, lng))
print timezone.dst

méthode liée America/Anchorage.dst de DstTzInfo

Amérique/Ancrage' LMT-1 jour, 14:00:00 MST

si vous préférez éviter un service web, vous pouvez récupérer cette information à partir du navigateur comme ceci:

var d = new Date();
var usertime = d.toLocaleString();

//some browsers / OSs provide the timezone name in their local string
var tzsregex = /\b(ACDT|ACST|ACT|ADT|AEDT|AEST|AFT|AKDT|AKST|AMST|AMT|ART|AST|AWDT|AWST|AZOST|AZT|BDT|BIOT|BIT|BOT|BRT|BST|BTT|CAT|CCT|CDT|CEDT|CEST|CET|CHADT|CHAST|CIST|CKT|CLST|CLT|COST|COT|CST|CT|CVT|CXT|CHST|DFT|EAST|EAT|ECT|EDT|EEDT|EEST|EET|EST|FJT|FKST|FKT|GALT|GET|GFT|GILT|GIT|GMT|GST|GYT|HADT|HAEC|HAST|HKT|HMT|HST|ICT|IDT|IRKT|IRST|IST|JST|KRAT|KST|LHST|LINT|MART|MAGT|MDT|MET|MEST|MIT|MSD|MSK|MST|MUT|MYT|NDT|NFT|NPT|NST|NT|NZDT|NZST|OMST|PDT|PETT|PHOT|PKT|PST|RET|SAMT|SAST|SBT|SCT|SGT|SLT|SST|TAHT|THA|UYST|UYT|VET|VLAT|WAT|WEDT|WEST|WET|WST|YAKT|YEKT)\b/gi;

//in other browsers the timezone needs to be estimated based on the offset
var timezonenames = {"UTC+0":"GMT","UTC+1":"CET","UTC+2":"EET","UTC+3":"EEDT","UTC+3.5":"IRST","UTC+4":"MSD","UTC+4.5":"AFT","UTC+5":"PKT","UTC+5.5":"IST","UTC+6":"BST","UTC+6.5":"MST","UTC+7":"THA","UTC+8":"AWST","UTC+9":"AWDT","UTC+9.5":"ACST","UTC+10":"AEST","UTC+10.5":"ACDT","UTC+11":"AEDT","UTC+11.5":"NFT","UTC+12":"NZST","UTC-1":"AZOST","UTC-2":"GST","UTC-3":"BRT","UTC-3.5":"NST","UTC-4":"CLT","UTC-4.5":"VET","UTC-5":"EST","UTC-6":"CST","UTC-7":"MST","UTC-8":"PST","UTC-9":"AKST","UTC-9.5":"MIT","UTC-10":"HST","UTC-11":"SST","UTC-12":"BIT"};

var timezone = usertime.match(tzsregex);
if (timezone) {
    timezone = timezone[timezone.length-1];
} else {
    var offset = -1*d.getTimezoneOffset()/60;
    offset = "UTC" + (offset >= 0 ? "+" + offset : offset);
    timezone = timezonenames[offset];
}

//there are 3 variables can use to see the timezone
// usertime - full date
// offset - UTC offset time
// timezone - country

console.log('Full Date: ' + usertime);
console.log('UTC Offset: ' + offset);
console.log('Country Code Timezone: ' + timezone);

Dans mon cas c'est l'impression:

Date Complète: 27/01/2014 16:53:37 UTC Offset: UTC-3 Country Code Timezone: BRT

J'espère que ça peut être utile.