/*
 *  RapidMiner
 *
 *  Copyright (C) 2001-2014 by RapidMiner and the contributors
 *
 *  Complete list of developers available at our web site:
 *
 *       http://rapidminer.com
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Affero General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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 Affero General Public License for more details.
 *
 *  You should have received a copy of the GNU Affero General Public License
 *  along with this program.  If not, see http://www.gnu.org/licenses/.
 */
package com.rapidminer.tools.math.similarity.numerical;

import com.rapidminer.example.ExampleSet;
import com.rapidminer.example.Tools;
import com.rapidminer.operator.OperatorException;
import com.rapidminer.tools.math.similarity.DistanceMeasure;

/**
 * This measure returns the maximal individual absolute distance of both examples in any component.
 * 
 * @author Sebastian Land, Michael Wurst
 */
public class ChebychevNumericalDistance extends DistanceMeasure {

	private static final long serialVersionUID = -2995153254013795660L;

	@Override
	public double calculateDistance(double[] value1, double[] value2) {
		double max = Double.NEGATIVE_INFINITY;
		for (int i = 0; i < value1.length; i++) {
			double v1 = value1[i];
			double v2 = value2[i];
			if ((!Double.isNaN(v1)) && (!Double.isNaN(v2))) {
				double d = Math.abs(v1 - v2);
				if (d > max)
					max = d;
			}
		}
		if (max > Double.NEGATIVE_INFINITY)
			return max;
		else
			return Double.NaN;
	}

	@Override
	public double calculateSimilarity(double[] value1, double[] value2) {
		return -calculateDistance(value1, value2);
	}

	@Override
	public void init(ExampleSet exampleSet) throws OperatorException {
	    super.init(exampleSet);
	    Tools.onlyNumericalAttributes(exampleSet, "value based similarities");
	}

	@Override
	public String toString() {
		return "Chebychev numerical distance";
	}

}