01 /*
02 * Java Genetic Algorithm Library (jenetics-3.5.0).
03 * Copyright (c) 2007-2016 Franz Wilhelmstötter
04 *
05 * Licensed under the Apache License, Version 2.0 (the "License");
06 * you may not use this file except in compliance with the License.
07 * You may obtain a copy of the License at
08 *
09 * 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 * Author:
18 * Franz Wilhelmstötter (franz.wilhelmstoetter@gmx.at)
19 */
20 package org.jenetics.engine;
21
22 import java.util.function.Predicate;
23
24 import org.jenetics.Optimize;
25
26 /**
27 * @author <a href="mailto:franz.wilhelmstoetter@gmx.at">Franz Wilhelmstötter</a>
28 * @since 3.0
29 * @version 3.0
30 */
31 final class SteadyFitnessLimit<C extends Comparable<? super C>>
32 implements Predicate<EvolutionResult<?, C>>
33 {
34 private final int _generations;
35
36 private boolean _proceed = true;
37 private int _stable = 0;
38 private C _fitness;
39
40 public SteadyFitnessLimit(final int generations) {
41 if (generations < 1) {
42 throw new IllegalArgumentException("Generations < 1: " + generations);
43 }
44 _generations = generations;
45 }
46
47 @Override
48 public boolean test(final EvolutionResult<?, C> result) {
49 if (!_proceed) return false;
50
51 if (_fitness == null) {
52 _fitness = result.getBestFitness();
53 _stable = 1;
54 } else {
55 final Optimize opt = result.getOptimize();
56 if (opt.compare(_fitness, result.getBestFitness()) >= 0) {
57 _proceed = ++_stable <= _generations;
58 } else {
59 _fitness = result.getBestFitness();
60 _stable = 1;
61 }
62 }
63
64 return _proceed;
65 }
66 }
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