001 /* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017 package org.apache.commons.math.genetics; 018 019 /** 020 * Stops after a fixed number of generations. Each time 021 * {@link #isSatisfied(Population)} is invoked, a generation counter is 022 * incremented. Once the counter reaches the configured 023 * <code>maxGenerations</code> value, {@link #isSatisfied(Population)} returns 024 * true. 025 * 026 * @version $Revision: 811685 $ $Date: 2009-09-05 19:36:48 +0200 (sam. 05 sept. 2009) $ 027 * @since 2.0 028 */ 029 public class FixedGenerationCount implements StoppingCondition { 030 /** Number of generations that have passed */ 031 private int numGenerations = 0; 032 033 /** Maximum number of generations (stopping criteria) */ 034 private final int maxGenerations; 035 036 /** 037 * Create a new FixedGenerationCount instance. 038 * 039 * @param maxGenerations number of generations to evolve 040 */ 041 public FixedGenerationCount(int maxGenerations) { 042 if (maxGenerations <= 0) 043 throw new IllegalArgumentException("The number of generations has to be >= 0"); 044 this.maxGenerations = maxGenerations; 045 } 046 047 /** 048 * Determine whether or not the given number of generations have passed. 049 * Increments the number of generations counter if the maximum has not 050 * been reached. 051 * 052 * @param population ignored (no impact on result) 053 * @return <code>true</code> IFF the maximum number of generations has been exceeded 054 */ 055 public boolean isSatisfied(Population population) { 056 if (this.numGenerations < this.maxGenerations) { 057 numGenerations++; 058 return false; 059 } 060 return true; 061 } 062 063 /** 064 * @return the number of generations that have passed 065 */ 066 public int getNumGenerations() { 067 return numGenerations; 068 } 069 070 }