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date | Tue, 04 Jan 2011 10:02:07 +0100 |
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<HTML> <BODY BGCOLOR="white"> <PRE> <FONT color="green">001</FONT> /*<a name="line.1"></a> <FONT color="green">002</FONT> * Licensed to the Apache Software Foundation (ASF) under one or more<a name="line.2"></a> <FONT color="green">003</FONT> * contributor license agreements. See the NOTICE file distributed with<a name="line.3"></a> <FONT color="green">004</FONT> * this work for additional information regarding copyright ownership.<a name="line.4"></a> <FONT color="green">005</FONT> * The ASF licenses this file to You under the Apache License, Version 2.0<a name="line.5"></a> <FONT color="green">006</FONT> * (the "License"); you may not use this file except in compliance with<a name="line.6"></a> <FONT color="green">007</FONT> * the License. You may obtain a copy of the License at<a name="line.7"></a> <FONT color="green">008</FONT> *<a name="line.8"></a> <FONT color="green">009</FONT> * http://www.apache.org/licenses/LICENSE-2.0<a name="line.9"></a> <FONT color="green">010</FONT> *<a name="line.10"></a> <FONT color="green">011</FONT> * Unless required by applicable law or agreed to in writing, software<a name="line.11"></a> <FONT color="green">012</FONT> * distributed under the License is distributed on an "AS IS" BASIS,<a name="line.12"></a> <FONT color="green">013</FONT> * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.<a name="line.13"></a> <FONT color="green">014</FONT> * See the License for the specific language governing permissions and<a name="line.14"></a> <FONT color="green">015</FONT> * limitations under the License.<a name="line.15"></a> <FONT color="green">016</FONT> */<a name="line.16"></a> <FONT color="green">017</FONT> package org.apache.commons.math.genetics;<a name="line.17"></a> <FONT color="green">018</FONT> <a name="line.18"></a> <FONT color="green">019</FONT> import java.util.ArrayList;<a name="line.19"></a> <FONT color="green">020</FONT> import java.util.List;<a name="line.20"></a> <FONT color="green">021</FONT> <a name="line.21"></a> <FONT color="green">022</FONT> <a name="line.22"></a> <FONT color="green">023</FONT> /**<a name="line.23"></a> <FONT color="green">024</FONT> * One point crossover policy. A random crossover point is selected and the<a name="line.24"></a> <FONT color="green">025</FONT> * first part from each parent is copied to the corresponding child, and the<a name="line.25"></a> <FONT color="green">026</FONT> * second parts are copied crosswise.<a name="line.26"></a> <FONT color="green">027</FONT> *<a name="line.27"></a> <FONT color="green">028</FONT> * Example:<a name="line.28"></a> <FONT color="green">029</FONT> * <pre><a name="line.29"></a> <FONT color="green">030</FONT> * -C- denotes a crossover point<a name="line.30"></a> <FONT color="green">031</FONT> * -C- -C-<a name="line.31"></a> <FONT color="green">032</FONT> * p1 = (1 0 1 0 0 1 | 0 1 1) X p2 = (0 1 1 0 1 0 | 1 1 1)<a name="line.32"></a> <FONT color="green">033</FONT> * \------------/ \-----/ \------------/ \-----/<a name="line.33"></a> <FONT color="green">034</FONT> * || (*) || (**)<a name="line.34"></a> <FONT color="green">035</FONT> * VV (**) VV (*)<a name="line.35"></a> <FONT color="green">036</FONT> * /------------\ /-----\ /------------\ /-----\<a name="line.36"></a> <FONT color="green">037</FONT> * c1 = (1 0 1 0 0 1 | 1 1 1) X p2 = (0 1 1 0 1 0 | 0 1 1)<a name="line.37"></a> <FONT color="green">038</FONT> * </pre><a name="line.38"></a> <FONT color="green">039</FONT> *<a name="line.39"></a> <FONT color="green">040</FONT> * This policy works only on {@link AbstractListChromosome}, and therefore it<a name="line.40"></a> <FONT color="green">041</FONT> * is parametrized by T. Moreover, the chromosomes must have same lengths.<a name="line.41"></a> <FONT color="green">042</FONT> *<a name="line.42"></a> <FONT color="green">043</FONT> * @param <T> generic type of the {@link AbstractListChromosome}s for crossover<a name="line.43"></a> <FONT color="green">044</FONT> * @since 2.0<a name="line.44"></a> <FONT color="green">045</FONT> * @version $Revision: 903046 $ $Date: 2010-01-25 21:07:26 -0500 (Mon, 25 Jan 2010) $<a name="line.45"></a> <FONT color="green">046</FONT> *<a name="line.46"></a> <FONT color="green">047</FONT> */<a name="line.47"></a> <FONT color="green">048</FONT> public class OnePointCrossover<T> implements CrossoverPolicy {<a name="line.48"></a> <FONT color="green">049</FONT> <a name="line.49"></a> <FONT color="green">050</FONT> /**<a name="line.50"></a> <FONT color="green">051</FONT> * Performs one point crossover. A random crossover point is selected and the<a name="line.51"></a> <FONT color="green">052</FONT> * first part from each parent is copied to the corresponding child, and the<a name="line.52"></a> <FONT color="green">053</FONT> * second parts are copied crosswise.<a name="line.53"></a> <FONT color="green">054</FONT> *<a name="line.54"></a> <FONT color="green">055</FONT> * Example:<a name="line.55"></a> <FONT color="green">056</FONT> * -C- denotes a crossover point<a name="line.56"></a> <FONT color="green">057</FONT> * -C- -C-<a name="line.57"></a> <FONT color="green">058</FONT> * p1 = (1 0 1 0 0 1 | 0 1 1) X p2 = (0 1 1 0 1 0 | 1 1 1)<a name="line.58"></a> <FONT color="green">059</FONT> * \------------/ \-----/ \------------/ \-----/<a name="line.59"></a> <FONT color="green">060</FONT> * || (*) || (**)<a name="line.60"></a> <FONT color="green">061</FONT> * VV (**) VV (*)<a name="line.61"></a> <FONT color="green">062</FONT> * /------------\ /-----\ /------------\ /-----\<a name="line.62"></a> <FONT color="green">063</FONT> * c1 = (1 0 1 0 0 1 | 1 1 1) X p2 = (0 1 1 0 1 0 | 0 1 1)<a name="line.63"></a> <FONT color="green">064</FONT> *<a name="line.64"></a> <FONT color="green">065</FONT> * @param first first parent (p1)<a name="line.65"></a> <FONT color="green">066</FONT> * @param second second parent (p2)<a name="line.66"></a> <FONT color="green">067</FONT> * @return pair of two children (c1,c2)<a name="line.67"></a> <FONT color="green">068</FONT> */<a name="line.68"></a> <FONT color="green">069</FONT> @SuppressWarnings("unchecked") // OK because of instanceof checks<a name="line.69"></a> <FONT color="green">070</FONT> public ChromosomePair crossover(Chromosome first, Chromosome second) {<a name="line.70"></a> <FONT color="green">071</FONT> if (! (first instanceof AbstractListChromosome<?> && second instanceof AbstractListChromosome<?>)) {<a name="line.71"></a> <FONT color="green">072</FONT> throw new IllegalArgumentException("One point crossover works on FixedLengthChromosomes only.");<a name="line.72"></a> <FONT color="green">073</FONT> }<a name="line.73"></a> <FONT color="green">074</FONT> return crossover((AbstractListChromosome<T>) first, (AbstractListChromosome<T>) second);<a name="line.74"></a> <FONT color="green">075</FONT> }<a name="line.75"></a> <FONT color="green">076</FONT> <a name="line.76"></a> <FONT color="green">077</FONT> <a name="line.77"></a> <FONT color="green">078</FONT> /**<a name="line.78"></a> <FONT color="green">079</FONT> * Helper for {@link #crossover(Chromosome, Chromosome)}. Performs the actual crossover.<a name="line.79"></a> <FONT color="green">080</FONT> *<a name="line.80"></a> <FONT color="green">081</FONT> * @param first the first chromosome.<a name="line.81"></a> <FONT color="green">082</FONT> * @param second the second chromosome.<a name="line.82"></a> <FONT color="green">083</FONT> * @return the pair of new chromosomes that resulted from the crossover.<a name="line.83"></a> <FONT color="green">084</FONT> */<a name="line.84"></a> <FONT color="green">085</FONT> private ChromosomePair crossover(AbstractListChromosome<T> first, AbstractListChromosome<T> second) {<a name="line.85"></a> <FONT color="green">086</FONT> int length = first.getLength();<a name="line.86"></a> <FONT color="green">087</FONT> if (length != second.getLength())<a name="line.87"></a> <FONT color="green">088</FONT> throw new IllegalArgumentException("Both chromosomes must have same lengths.");<a name="line.88"></a> <FONT color="green">089</FONT> <a name="line.89"></a> <FONT color="green">090</FONT> // array representations of the parents<a name="line.90"></a> <FONT color="green">091</FONT> List<T> parent1Rep = first.getRepresentation();<a name="line.91"></a> <FONT color="green">092</FONT> List<T> parent2Rep = second.getRepresentation();<a name="line.92"></a> <FONT color="green">093</FONT> // and of the children<a name="line.93"></a> <FONT color="green">094</FONT> ArrayList<T> child1Rep = new ArrayList<T> (first.getLength());<a name="line.94"></a> <FONT color="green">095</FONT> ArrayList<T> child2Rep = new ArrayList<T> (second.getLength());<a name="line.95"></a> <FONT color="green">096</FONT> <a name="line.96"></a> <FONT color="green">097</FONT> // select a crossover point at random (0 and length makes no sense)<a name="line.97"></a> <FONT color="green">098</FONT> int crossoverIndex = 1 + (GeneticAlgorithm.getRandomGenerator().nextInt(length-2));<a name="line.98"></a> <FONT color="green">099</FONT> <a name="line.99"></a> <FONT color="green">100</FONT> // copy the first part<a name="line.100"></a> <FONT color="green">101</FONT> for (int i = 0; i < crossoverIndex; i++) {<a name="line.101"></a> <FONT color="green">102</FONT> child1Rep.add(parent1Rep.get(i));<a name="line.102"></a> <FONT color="green">103</FONT> child2Rep.add(parent2Rep.get(i));<a name="line.103"></a> <FONT color="green">104</FONT> }<a name="line.104"></a> <FONT color="green">105</FONT> // and switch the second part<a name="line.105"></a> <FONT color="green">106</FONT> for (int i = crossoverIndex; i < length; i++) {<a name="line.106"></a> <FONT color="green">107</FONT> child1Rep.add(parent2Rep.get(i));<a name="line.107"></a> <FONT color="green">108</FONT> child2Rep.add(parent1Rep.get(i));<a name="line.108"></a> <FONT color="green">109</FONT> }<a name="line.109"></a> <FONT color="green">110</FONT> <a name="line.110"></a> <FONT color="green">111</FONT> return new ChromosomePair(<a name="line.111"></a> <FONT color="green">112</FONT> first.newFixedLengthChromosome(child1Rep),<a name="line.112"></a> <FONT color="green">113</FONT> second.newFixedLengthChromosome(child2Rep)<a name="line.113"></a> <FONT color="green">114</FONT> );<a name="line.114"></a> <FONT color="green">115</FONT> }<a name="line.115"></a> <FONT color="green">116</FONT> <a name="line.116"></a> <FONT color="green">117</FONT> }<a name="line.117"></a> </PRE> </BODY> </HTML>