Geo Location Helper Methods

calculateCenter.js

// Calculate center geo-coords from list of location coordinates
function calculateCenterPoint(data, latProperty = "latitude", lonProperty = "longitude") {
  var num_coords = data.length;

  var X = 0.0;
  var Y = 0.0;
  var Z = 0.0;

  for (i = 0; i < data.length; i++) {
    var lat = data[i][latProperty] * Math.PI / 180;
    var lon = data[i][lonProperty] * Math.PI / 180;

    var a = Math.cos(lat) * Math.cos(lon);
    var b = Math.cos(lat) * Math.sin(lon);
    var c = Math.sin(lat);

    X += a;
    Y += b;
    Z += c;
  }

  X /= num_coords;
  Y /= num_coords;
  Z /= num_coords;

  var lon = Math.atan2(Y, X);
  var hyp = Math.sqrt(X * X + Y * Y);
  var lat = Math.atan2(Z, hyp);

  var newX = (lat * 180 / Math.PI);
  var newY = (lon * 180 / Math.PI);

  var ret = {};
  ret[latProperty] = newX;
  ret[lonProperty] = newY;
  return ret;
}

calculateDistance.js

// Calculate distance between two location coordinates
function calculateDistance(from, to, unit, latProperty = "latitude", lonProperty = "longitude") {
  var radlat1 = Math.PI * from[latProperty] / 180;
  var radlat2 = Math.PI * to[latProperty] / 180;
  var radlon1 = Math.PI * from[lonProperty] / 180;
  var radlon2 = Math.PI * to[lonProperty] / 180;
  var theta = from[lonProperty] - to[lonProperty];
  var radtheta = Math.PI * theta / 180;
  var dist = Math.sin(radlat1) * Math.sin(radlat2) + Math.cos(radlat1) * Math.cos(radlat2) * Math.cos(radtheta);
  dist = Math.acos(dist);
  dist = dist * 180 / Math.PI;
  dist = dist * 60 * 1.1515;
  if (unit === "K") {
    // Unit in Kilometers
    dist = dist * 1.609344
  } else if (unit === "N") {
    // Unit in Nautical Miles
    dist = dist * 0.8684
  } else if (unit === "M") {
    // Unit in Miles
    dist = dist;
  } else if (unit === "y") {
    // Unit in Yards
    dist = dist * 1760;
  } else {
    // Default to unit in meters
    dist = (dist * 1.609344) * 1000
  }
  return dist;
}