gistfile1.java

class GeoClusterer {

	private final double maxDistance;
	private final List<GeoCluster> clusters = Lists.newArrayList();

	public GeoClusterer(double maxDistance, DistanceUnit unit) {
		this.maxDistance = unit.convert(maxDistance, unit, DistanceUnit.KILOMETERS);
	}

	public GeoCluster add(GeoPoint point) {
		GeoCluster cluster = null;
		double distance = Double.MAX_VALUE;
		for (GeoCluster c : clusters) {
			double d = distance(c.center(), point);
			if (d < distance && d <= maxDistance) {
				d = distance;
				cluster = c;
			}
		}
		if (cluster == null) {
			cluster = new GeoCluster();
			clusters.add(cluster);
		}
		cluster.add(point);
		return cluster;
	}

	private double distance(GeoPoint left, GeoPoint right) {
		return GeoDistance.ARC.calculate(left.getLat(), left.getLon(),
			right.getLat(), right.getLon(), DistanceUnit.KILOMETERS);
	}

	public List<GeoCluster> getClusters() {
		return clusters;
	}
}

class GeoCluster {

	private int size;
	private GeoPoint center;

	public void add(GeoPoint point) {
		++size;
		if (center == null) {
			center = point;
		}
		else {
			double lat = (center.getLat() * (size - 1) + point.getLat()) / size;
			double lon = (center.getLon() * (size - 1) + point.getLon()) / size;
			center = new GeoPoint(lat, lon);
		}
	}

	public int size() {
		return size;
	}

	public GeoPoint center() {
		return center;
	}
}