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.math.genetics;
18
19 /**
20 * Stops after a fixed number of generations. Each time
21 * {@link #isSatisfied(Population)} is invoked, a generation counter is
22 * incremented. Once the counter reaches the configured
23 * <code>maxGenerations</code> value, {@link #isSatisfied(Population)} returns
24 * true.
25 *
26 * @version $Revision: 799857 $ $Date: 2009-08-01 09:07:12 -0400 (Sat, 01 Aug 2009) $
27 * @since 2.0
28 */
29 public class FixedGenerationCount implements StoppingCondition {
30 /** Number of generations that have passed */
31 private int numGenerations = 0;
32
33 /** Maximum number of generations (stopping criteria) */
34 private final int maxGenerations;
35
36 /**
37 * Create a new FixedGenerationCount instance.
38 *
39 * @param maxGenerations number of generations to evolve
40 */
41 public FixedGenerationCount(int maxGenerations) {
42 if (maxGenerations <= 0)
43 throw new IllegalArgumentException("The number of generations has to be >= 0");
44 this.maxGenerations = maxGenerations;
45 }
46
47 /**
48 * Determine whether or not the given number of generations have passed.
49 * Increments the number of generations counter if the maximum has not
50 * been reached.
51 *
52 * @param population ignored (no impact on result)
53 * @return <code>true</code> IFF the maximum number of generations has been exceeded
54 */
55 public boolean isSatisfied(Population population) {
56 if (this.numGenerations < this.maxGenerations) {
57 numGenerations++;
58 return false;
59 }
60 return true;
61 }
62
63 /**
64 * @return the number of generations that have passed
65 */
66 public int getNumGenerations() {
67 return numGenerations;
68 }
69
70 }