CrossCorrelationDistance.java

import weka.core.*;

public class CrossCorrelationDistance extends NormalizableDistance {

    @Override
    public double distance(Instance first, Instance second) {

        double mx = 0;
        double my = 0;

        for(int i=0; i<first.numValues(); i++) {
            mx += first.value(i);
            my += second.value(i);
        }
        mx /= first.numValues();
        my /= second.numValues();

        double num = 0;
        double sumX = 0;
        double sumY = 0;

        for(int i=0; i<first.numValues(); i++) {
            double x = first.value(i);
            double y = second.value(i);

            num += (x-mx) * (y-my);
            sumX += Math.pow(x-mx, 2);
            sumY += Math.pow(y-my, 2);
        }

        double xcorr = num / (Math.sqrt(sumX) * Math.sqrt(sumY));

        if(Double.isNaN(xcorr))
            xcorr = 0;

        return xcorr;
    }

    @Override
    public String globalInfo() {
        return null;
    }

    @Override
    protected double updateDistance(double currDist, double diff) {
        return 0;
    }

    public String getRevision() {
        return null;
    }
}