1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 package org.apache.commons.math4.legacy.genetics; 18 19 import org.apache.commons.math4.legacy.exception.NumberIsTooSmallException; 20 21 /** 22 * Stops after a fixed number of generations. 23 * <p> 24 * Each time {@link #isSatisfied(Population)} is invoked, a generation counter 25 * is incremented. Once the counter reaches the configured 26 * {@code maxGenerations} value, {@link #isSatisfied(Population)} returns true. 27 * 28 * @since 2.0 29 */ 30 public class FixedGenerationCount implements StoppingCondition { 31 /** Number of generations that have passed. */ 32 private int numGenerations; 33 34 /** Maximum number of generations (stopping criteria). */ 35 private final int maxGenerations; 36 37 /** 38 * Create a new FixedGenerationCount instance. 39 * 40 * @param maxGenerations number of generations to evolve 41 * @throws NumberIsTooSmallException if the number of generations is < 1 42 */ 43 public FixedGenerationCount(final int maxGenerations) throws NumberIsTooSmallException { 44 if (maxGenerations <= 0) { 45 throw new NumberIsTooSmallException(maxGenerations, 1, true); 46 } 47 this.maxGenerations = maxGenerations; 48 } 49 50 /** 51 * Determine whether or not the given number of generations have passed. Increments the number of generations 52 * counter if the maximum has not been reached. 53 * 54 * @param population ignored (no impact on result) 55 * @return <code>true</code> IFF the maximum number of generations has been exceeded 56 */ 57 @Override 58 public boolean isSatisfied(final Population population) { 59 if (this.numGenerations < this.maxGenerations) { 60 numGenerations++; 61 return false; 62 } 63 return true; 64 } 65 66 /** 67 * Returns the number of generations that have already passed. 68 * @return the number of generations that have passed 69 */ 70 public int getNumGenerations() { 71 return numGenerations; 72 } 73 }