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.math3.genetics; 018 019 import org.apache.commons.math3.exception.NumberIsTooSmallException; 020 021 /** 022 * Stops after a fixed number of generations. Each time {@link #isSatisfied(Population)} is invoked, a generation 023 * counter is incremented. Once the counter reaches the configured <code>maxGenerations</code> value, 024 * {@link #isSatisfied(Population)} returns true. 025 * 026 * @version $Id: FixedGenerationCount.java 1416643 2012-12-03 19:37:14Z tn $ 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 * @throws NumberIsTooSmallException if the number of generations is < 1 041 */ 042 public FixedGenerationCount(final int maxGenerations) throws NumberIsTooSmallException { 043 if (maxGenerations <= 0) { 044 throw new NumberIsTooSmallException(maxGenerations, 1, true); 045 } 046 this.maxGenerations = maxGenerations; 047 } 048 049 /** 050 * Determine whether or not the given number of generations have passed. Increments the number of generations 051 * counter if the maximum has not been reached. 052 * 053 * @param population ignored (no impact on result) 054 * @return <code>true</code> IFF the maximum number of generations has been exceeded 055 */ 056 public boolean isSatisfied(final Population population) { 057 if (this.numGenerations < this.maxGenerations) { 058 numGenerations++; 059 return false; 060 } 061 return true; 062 } 063 064 /** 065 * Returns the number of generations that have already passed. 066 * @return the number of generations that have passed 067 */ 068 public int getNumGenerations() { 069 return numGenerations; 070 } 071 072 }