/**
* Copyright (C) 2001-2017 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.SimilarityMeasure;
/**
* Specialized similarity that takes the maximum product of two feature values. If this value is
* zero, the similarity is undefined. This similarity measure is used mainly with features extracted
* from cluster models.
*
* @author Michael Wurst
*/
public class MaxProductSimilarity extends SimilarityMeasure {
private static final long serialVersionUID = -7476444724888001751L;
@Override
public double calculateSimilarity(double[] value1, double[] value2) {
double max = Double.NEGATIVE_INFINITY;
for (int i = 0; i < value1.length; i++) {
if ((!Double.isNaN(value1[i])) && (!Double.isNaN(value2[i]))) {
double v = value2[i] * value1[i];
if (v > max) {
max = v;
}
}
}
if (max > 0.0) {
return max;
} else {
return Double.NaN;
}
}
@Override
public double calculateDistance(double[] value1, double[] value2) {
return -calculateSimilarity(value1, value2);
}
@Override
public void init(ExampleSet exampleSet) throws OperatorException {
super.init(exampleSet);
Tools.onlyNumericalAttributes(exampleSet, "value based similarities");
}
@Override
public String toString() {
return "Max product numerical similarity";
}
}