Edge.java

/* Project 3
 * Abdul Moid Munawar, amunawar, amunawar@u.rochester.edu
 * Moazzam Salman, msalman, msalman@u.rochseter.edu
 */
public class Edge {
	String id;
	double weight;
	private static final int RADIUS_EARTH = 3959; // Approx Earth radius in MILEs
	// constructor
	public Edge(String id, Node o, Node d) {
		
		this.weight = distance(o.lattitude, o.longitude, d.lattitude, d.longitude);
		this.id = id;
	}

	// find distance between two edges (in meters)
	// the following code for the Haversin Functon is taken from:
	// https://github.com/jasonwinn/haversine/blob/master/Haversine.java
	private static double haversin(double val) {
		return Math.pow(Math.sin(val / 2), 2);
	}
	private static double distance(double sLattitude, double sLongitude, double eLattitude, double eLongitude) {

		double disLat = Math.toRadians((eLattitude - sLattitude));
		double disLong = Math.toRadians((eLongitude - sLongitude));

		sLattitude = Math.toRadians(sLattitude);
		eLattitude = Math.toRadians(eLattitude);

		double a = haversin(disLat) + Math.cos(sLattitude) * Math.cos(eLattitude) * haversin(disLong);
		double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));

		return RADIUS_EARTH * c; 	// returns distance in miles
	}

}