/* * RapidMiner * * Copyright (C) 2001-2008 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.validation.clustering.itemdistribution; /** * Calculates an item distribution measure by summing up the squares of the fraction of items in each cluster. The result is inverted, thus the higher the value, the better the items are distributed. * * @author Michael Wurst * @version $Id: SumOfSquares.java,v 1.5 2008/09/12 10:30:06 tobiasmalbrecht Exp $ * */ public class SumOfSquares implements ItemDistributionMeasure { public double evaluate(int[] x, int n) { double result = 0; for (int i = 0; i < x.length; i++) result = result + (((double) x[i]) / n) * (((double) x[i]) / n); return result; } }