/*
 *  Copyright 2006 Columbia University.
 *
 *  This file is part of MEAPsoft.
 *
 *  MEAPsoft is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2 as
 *  published by the Free Software Foundation.
 *
 *  MEAPsoft is distributed in the hope that it will be useful, but
 *  WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with MEAPsoft; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 *  02110-1301 USA
 *
 *  See the file "COPYING" for the text of the license.
 */

package com.meapsoft;

/**
 * Simple distance metric calculating the euclidean distance (squared)
 * between two chunks' feature vectors.
 *
 * @author Mike Mandel (mim@ee.columbia.edu)
 * @author Ron Weiss (ronw@ee.columbia.edu)
 */

public class EuclideanDist extends ChunkDist 
{
    public EuclideanDist() {}
    public EuclideanDist(ChunkDist o) { super(o); }
    public EuclideanDist(int[] i) { super(i); }
    public EuclideanDist(ChunkDist o, int[] i) { super(o,i); }

    public double distance(Chunk ch1, Chunk ch2) 
    {
        FeatChunk c1 = null;
        FeatChunk c2 = null; 

        // this only works on FeatChunks
        try
        {
            c1 = (FeatChunk)ch1;
            c2 = (FeatChunk)ch2;
        }
        catch(ClassCastException e)
        {
            return super.distance(ch1, ch2);
        }

        double[] f1 = c1.getFeatures(featdim);
        double[] f2 = c2.getFeatures(featdim);
        double distSq = super.distance(c1, c2);

        for(int i=0; i<f1.length; i++)
            distSq += (f1[i] - f2[i]) * (f1[i] - f2[i]);

        return distSq;
    }
}