/*
* RapidMiner
*
* Copyright (C) 2001-2011 by Rapid-I and the contributors
*
* Complete list of developers available at our web site:
*
* http://rapid-i.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.operator.clustering.clusterer;
import java.util.Map;
import com.rapidminer.operator.clustering.HierarchicalClusterNode;
/**
* This class provides the AverageLinkageMethod, also called UPGMA, for the
* agglomerative clustering operator.
* @author Sebastian Land
*/
public class AverageLinkageMethod extends AbstractLinkageMethod {
private int[] clusterIds;
public AverageLinkageMethod(DistanceMatrix matrix, int[] clusterIds) {
super(matrix, clusterIds);
this.clusterIds = clusterIds;
}
@Override
public void updateDistances(DistanceMatrix matrix, int updatedRow, int unionedRow, Map<Integer, HierarchicalClusterNode> clusterMap) {
double weightUpdatedRow = clusterMap.get(clusterIds[updatedRow]).getNumberOfExamplesInSubtree();
double weightUnionedRow = clusterMap.get(clusterIds[unionedRow]).getNumberOfExamplesInSubtree();
double totalWeight = weightUnionedRow + weightUpdatedRow;
weightUnionedRow /= totalWeight;
weightUpdatedRow /= totalWeight;
for (int y = 0; y < matrix.getHeight(); y++) {
matrix.set(updatedRow, y, weightUpdatedRow * matrix.get(updatedRow, y) + weightUnionedRow * matrix.get(unionedRow, y));
}
}
}