001 /*
002 * Java Genetic Algorithm Library (jenetics-6.1.0).
003 * Copyright (c) 2007-2020 Franz Wilhelmstötter
004 *
005 * Licensed under the Apache License, Version 2.0 (the "License");
006 * you may not use this file except in compliance with the License.
007 * You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 *
017 * Author:
018 * Franz Wilhelmstötter (franz.wilhelmstoetter@gmail.com)
019 */
020 package io.jenetics.prog;
021
022 import static java.lang.String.format;
023 import static java.util.Objects.requireNonNull;
024
025 import java.util.Random;
026 import java.util.function.Function;
027
028 import io.jenetics.Gene;
029 import io.jenetics.util.ISeq;
030 import io.jenetics.util.RandomRegistry;
031
032 import io.jenetics.ext.AbstractTreeGene;
033 import io.jenetics.ext.util.TreeNode;
034
035 import io.jenetics.prog.op.Op;
036 import io.jenetics.prog.op.Program;
037
038 /**
039 * This gene represents a program, build upon an AST of {@link Op} functions.
040 * Because of the tight coupling with the {@link ProgramChromosome}, a
041 * {@code ProgramGene} can't be created directly. This reduces the the possible
042 * <em>error space</em>. Since the {@code ProgramGene} also is a {@code Tree},
043 * it can be easily used as result.
044 *
045 * <pre>{@code
046 * final ProgramGene<Double> program = engine.stream()
047 * .limit(300)
048 * .collect(EvolutionResult.toBestGenotype())
049 * .getGene();
050 *
051 * final double result = program.eval(3.4);
052 * }</pre>
053 *
054 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
055 * @version 5.2
056 * @since 3.9
057 */
058 public final class ProgramGene<A>
059 extends AbstractTreeGene<Op<A>, ProgramGene<A>>
060 implements Gene<Op<A>, ProgramGene<A>>, Function<A[], A>
061 {
062
063 private static final long serialVersionUID = 1L;
064
065 private final ISeq<? extends Op<A>> _operations;
066 private final ISeq<? extends Op<A>> _terminals;
067
068 ProgramGene(
069 final Op<A> op,
070 final int childOffset,
071 final ISeq<? extends Op<A>> operations,
072 final ISeq<? extends Op<A>> terminals
073 ) {
074 super(requireNonNull(get(op)), childOffset, op.arity());
075 _operations = requireNonNull(operations);
076 _terminals = requireNonNull(terminals);
077 }
078
079 private static <A> Op<A> get(final Op<A> op) {
080 final Op<A> instance = op.get();
081 if (instance != op && instance.arity() != op.arity()) {
082 throw new IllegalArgumentException(format(
083 "Original op and created op have different arity: %d != %d,",
084 instance.arity(), op.arity()
085 ));
086 }
087 return instance;
088 }
089
090 /**
091 * Evaluates this program gene (recursively) with the given variable values.
092 *
093 * @see ProgramGene#eval(Object[])
094 * @see ProgramChromosome#eval(Object[])
095 *
096 * @param args the input variables
097 * @return the evaluated value
098 * @throws NullPointerException if the given variable array is {@code null}
099 */
100 @Override
101 public A apply(final A[] args) {
102 checkTreeState();
103 return Program.eval(this, args);
104 }
105
106 /**
107 * Convenient method, which lets you apply the program function without
108 * explicitly create a wrapper array.
109 *
110 * @see ProgramGene#apply(Object[])
111 * @see ProgramChromosome#eval(Object[])
112 *
113 * @param args the function arguments
114 * @return the evaluated value
115 * @throws NullPointerException if the given variable array is {@code null}
116 */
117 @SafeVarargs
118 public final A eval(final A... args) {
119 return apply(args);
120 }
121
122 /**
123 * Return the allowed operations.
124 *
125 * @return the allowed operations
126 */
127 public ISeq<Op<A>> operations() {
128 return ISeq.upcast(_operations);
129 }
130
131 /**
132 * Return the allowed terminal operations.
133 *
134 * @return the allowed terminal operations
135 */
136 public ISeq<Op<A>> terminals() {
137 return ISeq.upcast(_terminals);
138 }
139
140 /**
141 * Creates a new {@link TreeNode} from this program gene.
142 *
143 * @since 5.0
144 *
145 * @return a new tree node value build from this program gene
146 */
147 public TreeNode<Op<A>> toTreeNode() {
148 return TreeNode.ofTree(this);
149 }
150
151 @Override
152 public ProgramGene<A> newInstance() {
153 final Random random = RandomRegistry.random();
154
155 Op<A> operation = value();
156 if (isLeaf()) {
157 operation = _terminals.get(random.nextInt(_terminals.length()));
158 } else {
159 final ISeq<Op<A>> operations = _operations.stream()
160 .filter(op -> op.arity() == value().arity())
161 .collect(ISeq.toISeq());
162
163 if (operations.length() > 1) {
164 operation = operations.get(random.nextInt(operations.length()));
165 }
166 }
167
168 return newInstance(operation);
169 }
170
171 /**
172 * Create a new program gene with the given operation.
173 *
174 * @param op the operation of the new program gene
175 * @return a new program gene with the given operation
176 * @throws NullPointerException if the given {@code op} is {@code null}
177 * @throws IllegalArgumentException if the arity of the given operation is
178 * different from the arity of current operation. This restriction
179 * ensures that only valid program genes are created by this method.
180 */
181 @Override
182 public ProgramGene<A> newInstance(final Op<A> op) {
183 if (value().arity() != op.arity()) {
184 throw new IllegalArgumentException(format(
185 "New operation must have same arity: %s[%d] != %s[%d]",
186 value().name(), value().arity(), op.name(), op.arity()
187 ));
188 }
189 return new ProgramGene<>(op, childOffset(), _operations, _terminals);
190 }
191
192 /**
193 * Return a new program gene with the given operation and the <em>local</em>
194 * tree structure.
195 *
196 * @param op the new operation
197 * @param childOffset the offset of the first node child within the
198 * chromosome
199 * @param childCount the number of children of the new tree gene
200 * @return a new tree gene with the given parameters
201 * @throws IllegalArgumentException if the {@code childCount} is smaller
202 * than zero
203 * @throws IllegalArgumentException if the operation arity is different from
204 * the {@code childCount}.
205 * @throws NullPointerException if the given {@code op} is {@code null}
206 */
207 @Override
208 public ProgramGene<A> newInstance(
209 final Op<A> op,
210 final int childOffset,
211 final int childCount
212 ) {
213 if (op.arity() != childCount) {
214 throw new IllegalArgumentException(format(
215 "Operation arity and child count are different: %d, != %d",
216 op.arity(), childCount
217 ));
218 }
219
220 return new ProgramGene<>(op, childOffset, _operations, _terminals);
221 }
222
223 }
|