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Calculate the center/average of multiple GeoLocation coordinates
/**
* Calculate the center/average of multiple GeoLocation coordinates
* Expects an array of objects with .latitude and .longitude properties
*
* @url http://stackoverflow.com/a/14231286/538646
*/
function averageGeolocation(coords) {
if (coords.length === 1) {
return coords[0];
}
let x = 0.0;
let y = 0.0;
let z = 0.0;
for (let coord of coords) {
let latitude = coord.latitude * Math.PI / 180;
let longitude = coord.longitude * Math.PI / 180;
x += Math.cos(latitude) * Math.cos(longitude);
y += Math.cos(latitude) * Math.sin(longitude);
z += Math.sin(latitude);
}
let total = coords.length;
x = x / total;
y = y / total;
z = z / total;
let centralLongitude = Math.atan2(y, x);
let centralSquareRoot = Math.sqrt(x * x + y * y);
let centralLatitude = Math.atan2(z, centralSquareRoot);
return {
latitude: centralLatitude * 180 / Math.PI,
longitude: centralLongitude * 180 / Math.PI
};
}
// expect ~ 37.790831, -122.407169
const sf = [{
latitude: 37.797749,
longitude: -122.412147
}, {
latitude: 37.789068,
longitude: -122.390604
}, {
latitude: 37.785269,
longitude: -122.421975
}];
console.log(averageGeolocation(sf));
// expect ~ 8.670552, -173.207864
const globe = [{ // Japan
latitude: 37.928969,
longitude: 138.979637
}, { // Nevada
latitude: 39.029788,
longitude: -119.594585
}, { // New Zealand
latitude: -39.298237,
longitude: 175.717917
}];
console.log(averageGeolocation(globe));
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