com.barrybecker4.optimization.parameter.distancecalculators.MagnitudeDistanceCalculator Maven / Gradle / Ivy

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/** Copyright by Barry G. Becker, 2013. Licensed under MIT License: http://www.opensource.org/licenses/MIT  */
package com.barrybecker4.optimization.parameter.distancecalculators;

import com.barrybecker4.optimization.parameter.ParameterArray;

/**
 *  @author Barry Becker
 */
public class MagnitudeDistanceCalculator implements DistanceCalculator {

    /**
     * The distance computation will be quite different for this than a regular parameter array.
     * We want the distance to represent a measure of the amount of similarity between two instances.
     * There are two ways in which instance can differ, and the weighting assigned to each may depend on the problem.
     *  - the length of the parameter array
     *  - the set of values in the parameter array.
     * Generally, the distance is greater the greater the number of parameters that are different.
     * @return the distance between this parameter array and another.
     */
    public double calculateDistance(ParameterArray pa1, ParameterArray pa2)  {

        int thisLength = pa1.size();
        int thatLength = pa2.size();

        double sum1  = 0;
        double sum2 = 0;
        for (int i=0; i< thisLength; i++) {
            sum1 +=  pa1.get(i).getValue();
        }
        for (int i=0; i< thatLength; i++) {
            sum2 += pa2.get(i).getValue();
        }

        return Math.abs(sum1 - sum2);
    }

}