isochrone-explorer/src/utils/geoUtils.js

A powerful isochrone and routing engine based on Dijkstra's algorithm for accurate travel time calculations.

function calculateDistance(coord1, coord2) {
    const R = 6371e3;
    const φ1 = coord1.lat * Math.PI / 180;
    const φ2 = coord2.lat * Math.PI / 180;
    const Δφ = (coord2.lat - coord1.lat) * Math.PI / 180;
    const Δλ = (coord2.lon - coord1.lon) * Math.PI / 180;
  
    const a = Math.sin(Δφ / 2) ** 2 +
              Math.cos(φ1) * Math.cos(φ2) *
              Math.sin(Δλ / 2) ** 2;
  
    const c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
    return R * c;
  }
  
  function reducePointsToPolygon(points) {
    return points.map(([lat, lon]) => [lon, lat]);
  }
  
  module.exports = { calculateDistance, reducePointsToPolygon };