001 /*
002 * Java Genetic Algorithm Library (jenetics-8.0.0).
003 * Copyright (c) 2007-2024 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.engine;
021
022 import static java.util.Objects.requireNonNull;
023
024 import java.util.function.Predicate;
025 import java.util.function.Supplier;
026
027 import io.jenetics.Gene;
028 import io.jenetics.Genotype;
029 import io.jenetics.Phenotype;
030 import io.jenetics.util.ISeq;
031
032 /**
033 * This interface defines the capability of creating {@link EvolutionStream}s
034 * from a given {@link EvolutionStart} object. It also decouples the engine's
035 * capability from the capability to create evolution streams. The purpose of
036 * this interface is similar to the {@link Iterable} interface.
037 *
038 * @see EvolutionStream
039 *
040 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
041 * @version 4.1
042 * @since 4.1
043 */
044 public interface EvolutionStreamable<
045 G extends Gene<?, G>,
046 C extends Comparable<? super C>
047 > {
048
049 /**
050 * Create a new, possibly <em>infinite</em>, evolution stream with the given
051 * evolution start. If an empty {@code Population} is given, the engine's
052 * genotype factory is used for creating the population. The given
053 * population might be the result of another engine, and this method allows
054 * to start the evolution with the outcome of a different engine.
055 * The fitness function is replaced by the one defined for this engine.
056 *
057 * @param start the data the evolution stream starts with
058 * @return a new <b>infinite</b> evolution stream
059 * @throws java.lang.NullPointerException if the given evolution
060 * {@code start} is {@code null}.
061 */
062 EvolutionStream<G, C>
063 stream(final Supplier<EvolutionStart<G, C>> start);
064
065 /**
066 * Create a new, possibly <em>infinite</em>, evolution stream with the given
067 * initial value. If an empty {@code Population} is given, the engines genotype
068 * factory is used for creating the population. The given population might
069 * be the result of another engine, and this method allows to start the
070 * evolution with the outcome of a different engine. The fitness function
071 * is replaced by the one defined for this engine.
072 *
073 * @param init the data the evolution stream is initialized with
074 * @return a new <b>infinite</b> evolution stream
075 * @throws java.lang.NullPointerException if the given evolution
076 * {@code start} is {@code null}.
077 */
078 EvolutionStream<G, C> stream(final EvolutionInit<G> init);
079
080
081 /* *************************************************************************
082 * Default interface methods.
083 * ************************************************************************/
084
085 /**
086 * Create a new, possibly <em>infinite</em>, evolution stream with a newly
087 * created population. This method is a shortcut for
088 * {@snippet lang="java":
089 * final EvolutionStream<G, C> stream = streamable
090 * .stream(() -> EvolutionStart.of(ISeq.empty(), 1));
091 * }
092 *
093 * @return a new evolution stream.
094 */
095 default EvolutionStream<G, C> stream() {
096 return stream((Supplier<EvolutionStart<G, C>>)EvolutionStart::empty);
097 }
098
099 /**
100 * Create a new, possibly <em>infinite</em>, evolution stream with the given
101 * evolution start. If an empty {@code Population} is given, the engine's genotype
102 * factory is used for creating the population. The given population might
103 * be the result of another engine, and this method allows to start the
104 * evolution with the outcome of a different engine. The fitness function
105 * is replaced by the one defined for this engine.
106 *
107 * @param start the data the evolution stream starts with
108 * @return a new <b>infinite</b> evolution iterator
109 * @throws java.lang.NullPointerException if the given evolution
110 * {@code start} is {@code null}.
111 */
112 default EvolutionStream<G, C>
113 stream(final EvolutionStart<G, C> start) {
114 return stream(() -> start);
115 }
116
117 /**
118 * Create a new {@code EvolutionStream} starting with a previously evolved
119 * {@link EvolutionResult}. The stream is initialized with the population
120 * of the given {@code result} and its total generation
121 * {@link EvolutionResult#totalGenerations()}.
122 *
123 * {@snippet lang="java":
124 * private static final Problem<Double, DoubleGene, Double>
125 * PROBLEM = Problem.of(
126 * x -> cos(0.5 + sin(x))*cos(x),
127 * Codecs.ofScalar(DoubleRange.of(0.0, 2.0*PI))
128 * );
129 *
130 * private static final Engine<DoubleGene, Double>
131 * ENGINE = Engine.builder(PROBLEM)
132 * .optimize(Optimize.MINIMUM)
133 * .offspringSelector(new RouletteWheelSelector<>())
134 * .build();
135 *
136 * public static void main(final String[] args) throws IOException {
137 * // Result of the first evolution run.
138 * final EvolutionResult<DoubleGene, Double> rescue = ENGINE.stream()
139 * .limit(Limits.bySteadyFitness(10))
140 * .collect(EvolutionResult.toBestEvolutionResult());
141 *
142 * // Save the result of the first run into a file.
143 * final Path path = Paths.get("result.bin");
144 * IO.object.write(rescue, path);
145 *
146 * // Load the previous result and continue evolution.
147 * @SuppressWarnings("unchecked")
148 * final EvolutionResult<DoubleGene, Double> result = ENGINE
149 * .stream((EvolutionResult<DoubleGene, Double>)IO.object.read(path))
150 * .limit(Limits.bySteadyFitness(20))
151 * .collect(EvolutionResult.toBestEvolutionResult());
152 *
153 * System.out.println(result.bestPhenotype());
154 * }
155 * }
156 *
157 * The example above shows how to save an {@link EvolutionResult} from a
158 * first run, save it to disk and continue the evolution.
159 *
160 * @param result the previously evolved {@code EvolutionResult}
161 * @return a new evolution stream, which continues a previous one
162 * @throws NullPointerException if the given evolution {@code result} is
163 * {@code null}
164 */
165 default EvolutionStream<G, C>
166 stream(final EvolutionResult<G, C> result) {
167 return stream(EvolutionStart.of(
168 result.population(),
169 result.generation()
170 ));
171 }
172
173 /**
174 * Create a new, possibly <em>infinite</em>, evolution stream with the given
175 * initial population. If an empty {@code Population} is given, the engine's
176 * genotype factory is used for creating the population. The given population
177 * might be the result of another engine, and this method allows to start the
178 * evolution with the outcome of a different engine. The fitness function
179 * is replaced by the one defined for this engine.
180 *
181 * @param population the initial individuals used for the evolution stream.
182 * Missing individuals are created and individuals not needed are
183 * skipped.
184 * @param generation the generation the stream starts from; must be greater
185 * than zero.
186 * @return a new evolution stream.
187 * @throws java.lang.NullPointerException if the given {@code population} is
188 * {@code null}.
189 * @throws IllegalArgumentException if the given {@code generation} is
190 * smaller then one
191 */
192 default EvolutionStream<G, C> stream(
193 final ISeq<Phenotype<G, C>> population,
194 final long generation
195 ) {
196 return stream(EvolutionStart.of(population, generation));
197 }
198
199 /**
200 * Create a new, possibly <em>infinite</em>, evolution stream with the given
201 * initial population. If an empty {@code Population} is given, the engine's
202 * genotype factory is used for creating the population. The given population
203 * might be the result of another engine, and this method allows to start the
204 * evolution with the outcome of a different engine. The fitness function
205 * is replaced by the one defined for this engine.
206 *
207 * @param population the initial individuals used for the evolution stream.
208 * Missing individuals are created and individuals not needed are
209 * skipped.
210 * @return a new evolution stream.
211 * @throws java.lang.NullPointerException if the given {@code population} is
212 * {@code null}.
213 */
214 default EvolutionStream<G, C> stream(final ISeq<Phenotype<G, C>> population) {
215 return stream(EvolutionStart.of(population, 1));
216 }
217
218 /**
219 * Create a new, possibly <em>infinite</em>, evolution stream with the given
220 * initial individuals. If an empty {@code Iterable} is given, the engine's
221 * genotype factory is used for creating the population.
222 *
223 * @param genotypes the initial individuals used for the evolution stream.
224 * Missing individuals are created and individuals not needed are
225 * skipped.
226 * @param generation the generation the stream starts from; must be greater
227 * than zero.
228 * @return a new evolution stream.
229 * @throws java.lang.NullPointerException if the given {@code genotypes} is
230 * {@code null}.
231 * @throws IllegalArgumentException if the given {@code generation} is
232 * smaller then one
233 */
234 default EvolutionStream<G, C> stream(
235 final Iterable<Genotype<G>> genotypes,
236 final long generation
237 ) {
238 return stream(EvolutionInit.of(ISeq.of(genotypes), generation));
239 }
240
241 /**
242 * Create a new, possibly <em>infinite</em>, evolution stream with the given
243 * initial individuals. If an empty {@code Iterable} is given, the engine's
244 * genotype factory is used for creating the population.
245 *
246 * @param genotypes the initial individuals used for the evolution stream.
247 * Missing individuals are created and individuals not needed are
248 * skipped.
249 * @return a new evolution stream.
250 * @throws java.lang.NullPointerException if the given {@code genotypes} is
251 * {@code null}.
252 */
253 default EvolutionStream<G, C>
254 stream(final Iterable<Genotype<G>> genotypes) {
255 return stream(genotypes, 1);
256 }
257
258 /**
259 * Return a new {@code EvolutionStreamable} instance where all created
260 * {@code EvolutionStream}s are limited by the given predicate. Since some
261 * predicates have to maintain internal state, a predicate {@code Supplier}
262 * must be given instead a plain limiting predicate.
263 *
264 * @param proceed the limiting predicate supplier.
265 * @return a new evolution-streamable object
266 * @throws NullPointerException if the give {@code predicate} is {@code null}
267 */
268 default EvolutionStreamable<G, C>
269 limit(final Supplier<? extends Predicate<? super EvolutionResult<G, C>>> proceed) {
270 requireNonNull(proceed);
271
272 return new EvolutionStreamable<>() {
273 @Override
274 public EvolutionStream<G, C>
275 stream(final Supplier<EvolutionStart<G, C>> start) {
276 return EvolutionStreamable.this.stream(start).limit(proceed.get());
277 }
278
279 @Override
280 public EvolutionStream<G, C> stream(final EvolutionInit<G> init) {
281 return EvolutionStreamable.this.stream(init).limit(proceed.get());
282 }
283 };
284 }
285
286 /**
287 * Return a new {@code EvolutionStreamable} instance where all created
288 * {@code EvolutionStream}s are limited to the given number of generations.
289 *
290 * @param generations the number of generations after the created evolution
291 * streams are truncated
292 * @return a new evolution-streamable object
293 * @throws IllegalArgumentException if the given {@code generations} is
294 * smaller than zero.
295 */
296 default EvolutionStreamable<G, C> limit(final long generations) {
297 return limit(() -> Limits.byFixedGeneration(generations));
298 }
299
300 }
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