FeatureDistanceFn.java

package mil.nga.giat.geowave.analytic.distance;

import org.opengis.feature.simple.SimpleFeature;

import com.vividsolutions.jts.geom.Coordinate;
import com.vividsolutions.jts.geom.Geometry;
import com.vividsolutions.jts.operation.distance.DistanceOp;

/**
 * Calculate distance between two SimpleFeatures. The distance is planar
 * distance between to two closest sides.
 * 
 * @see org.opengis.feature.simple.SimpleFeature
 * 
 */
public class FeatureDistanceFn implements
		DistanceFn<SimpleFeature>
{

	/**
	 * 
	 */
	private static final long serialVersionUID = 3824608959408031752L;
	private DistanceFn<Coordinate> coordinateDistanceFunction = new CoordinateCircleDistanceFn();

	public FeatureDistanceFn() {}

	public FeatureDistanceFn(
			final DistanceFn<Coordinate> coordinateDistanceFunction ) {
		super();
		this.coordinateDistanceFunction = coordinateDistanceFunction;
	}

	public DistanceFn<Coordinate> getCoordinateDistanceFunction() {
		return coordinateDistanceFunction;
	}

	public void setCoordinateDistanceFunction(
			final DistanceFn<Coordinate> coordinateDistanceFunction ) {
		this.coordinateDistanceFunction = coordinateDistanceFunction;
	}

	private Geometry getGeometry(
			final SimpleFeature x ) {
		for (final Object attr : x.getAttributes()) {
			if (attr instanceof Geometry) {
				return (Geometry) attr;
			}
		}
		return (Geometry) x.getDefaultGeometry();
	}

	@Override
	public double measure(
			final SimpleFeature x,
			final SimpleFeature y ) {

		double dist = Double.MAX_VALUE;
		final Coordinate[] coords = new DistanceOp(
				getGeometry(x),
				getGeometry(y)).nearestPoints();
		for (int i = 0; i < coords.length; i++) {
			for (int j = i + 1; j < coords.length; j++) {
				dist = Math.min(
						dist,
						coordinateDistanceFunction.measure(
								coords[j],
								coords[i]));
			}
		}
		return dist;
	}
}