01 /*
02 * Java Genetic Algorithm Library (jenetics-3.7.0).
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.tool;
21
22 import static java.lang.Math.max;
23
24 import org.jenetics.Gene;
25 import org.jenetics.Optimize;
26 import org.jenetics.Population;
27 import org.jenetics.Selector;
28 import org.jenetics.TournamentSelector;
29 import org.jenetics.TruncationSelector;
30
31 /**
32 * @author <a href="mailto:franz.wilhelmstoetter@gmx.at">Franz Wilhelmstötter</a>
33 * @version 3.4
34 * @since 3.4
35 */
36 public class ElitistSelector<
37 G extends Gene<?, G>,
38 C extends Comparable<? super C>
39 >
40 implements Selector<G, C>
41 {
42 private final TruncationSelector<G, C> _elitist = new TruncationSelector<>();
43 private final TournamentSelector<G, C> _rest = new TournamentSelector<>(3);
44
45 @Override
46 public Population<G, C> select(
47 final Population<G, C> population,
48 final int count,
49 final Optimize opt
50 ) {
51 return population.isEmpty() || count <= 0
52 ? new Population<>(0)
53 : append(
54 _elitist.select(population, 1, opt),
55 _rest.select(population, max(0, count - 1), opt));
56 }
57
58 private Population<G, C> append(
59 final Population<G, C> p1,
60 final Population<G, C> p2
61 ) {
62 p1.addAll(p2);
63 return p1;
64 }
65 }
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