001 /*
002 * Java Genetic Algorithm Library (jenetics-4.2.0).
003 * Copyright (c) 2007-2018 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 engines
052 * genotype factory is used for creating the population. The given
053 * population might be the result of an other engine and this method allows
054 * to start the evolution with the outcome of an different engine.
055 * The fitness function and the fitness scaler are replaced by the one
056 * defined for this engine.
057 *
058 * @param start the data the evolution stream starts with
059 * @return a new <b>infinite</b> evolution stream
060 * @throws java.lang.NullPointerException if the given evolution
061 * {@code start} is {@code null}.
062 */
063 public EvolutionStream<G, C>
064 stream(final Supplier<EvolutionStart<G, C>> start);
065
066 /**
067 * Create a new, possibly <em>infinite</em>, evolution stream with the given
068 * initial value. If an empty {@code Population} is given, the engines genotype
069 * factory is used for creating the population. The given population might
070 * be the result of an other engine and this method allows to start the
071 * evolution with the outcome of an different engine. The fitness function
072 * and the fitness scaler are replaced by the one defined for this engine.
073 *
074 * @param init the data the evolution stream is initialized with
075 * @return a new <b>infinite</b> evolution stream
076 * @throws java.lang.NullPointerException if the given evolution
077 * {@code start} is {@code null}.
078 */
079 public EvolutionStream<G, C> stream(final EvolutionInit<G> init);
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 * <pre>{@code
089 * final EvolutionStream<G, C> stream = streamable
090 * .stream(() -> EvolutionStart.of(ISeq.empty(), 1));
091 * }</pre>
092 *
093 * @return a new evolution stream.
094 */
095 public default EvolutionStream<G, C> stream() {
096 return stream(() -> EvolutionStart.of(ISeq.empty(), 1));
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 engines genotype
102 * factory is used for creating the population. The given population might
103 * be the result of an other engine and this method allows to start the
104 * evolution with the outcome of an different engine. The fitness function
105 * and the fitness scaler are 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 public 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#getTotalGenerations()}.
122 *
123 * <pre>{@code
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.getBestPhenotype());
154 * }
155 * }</pre>
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 public default EvolutionStream<G, C>
166 stream(final EvolutionResult<G, C> result) {
167 return stream(EvolutionStart.of(
168 result.getPopulation(),
169 result.getGeneration()
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 engines
176 * genotype factory is used for creating the population. The given population
177 * might be the result of an other engine and this method allows to start the
178 * evolution with the outcome of an different engine. The fitness function
179 * and the fitness scaler are 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 public 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 engines
202 * genotype factory is used for creating the population. The given population
203 * might be the result of an other engine and this method allows to start the
204 * evolution with the outcome of an different engine. The fitness function
205 * and the fitness scaler are 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 public default EvolutionStream<G, C>
215 stream(final ISeq<Phenotype<G, C>> population) {
216 return stream(EvolutionStart.of(population, 1));
217 }
218
219 /**
220 * Create a new, possibly <em>infinite</em>, evolution stream with the given
221 * initial individuals. If an empty {@code Iterable} is given, the engines
222 * genotype factory is used for creating the population.
223 *
224 * @param genotypes the initial individuals used for the evolution stream.
225 * Missing individuals are created and individuals not needed are
226 * skipped.
227 * @param generation the generation the stream starts from; must be greater
228 * than zero.
229 * @return a new evolution stream.
230 * @throws java.lang.NullPointerException if the given {@code genotypes} is
231 * {@code null}.
232 * @throws IllegalArgumentException if the given {@code generation} is
233 * smaller then one
234 */
235 public default EvolutionStream<G, C> stream(
236 final Iterable<Genotype<G>> genotypes,
237 final long generation
238 ) {
239 return stream(EvolutionInit.of(ISeq.of(genotypes), generation));
240 }
241
242 /**
243 * Create a new, possibly <em>infinite</em>, evolution stream with the given
244 * initial individuals. If an empty {@code Iterable} is given, the engines
245 * genotype factory is used for creating the population.
246 *
247 * @param genotypes the initial individuals used for the evolution stream.
248 * Missing individuals are created and individuals not needed are
249 * skipped.
250 * @return a new evolution stream.
251 * @throws java.lang.NullPointerException if the given {@code genotypes} is
252 * {@code null}.
253 */
254 public default EvolutionStream<G, C>
255 stream(final Iterable<Genotype<G>> genotypes) {
256 return stream(genotypes, 1);
257 }
258
259 /**
260 * Return a new {@code EvolutionStreamable} instance where all created
261 * {@code EvolutionStream}s are limited by the given predicate. Since some
262 * predicates has to maintain internal state, a predicate {@code Supplier}
263 * must be given instead a plain limiting predicate.
264 *
265 * @param proceed the limiting predicate supplier.
266 * @return a new evolution streamable object
267 * @throws NullPointerException if the give {@code predicate} is {@code null}
268 */
269 public default EvolutionStreamable<G, C>
270 limit(final Supplier<Predicate<? super EvolutionResult<G, C>>> proceed) {
271 requireNonNull(proceed);
272
273 return new EvolutionStreamable<G, C>() {
274 @Override
275 public EvolutionStream<G, C>
276 stream(final Supplier<EvolutionStart<G, C>> start) {
277 return EvolutionStreamable.this.stream(start).limit(proceed.get());
278 }
279
280 @Override
281 public EvolutionStream<G, C> stream(final EvolutionInit<G> init) {
282 return EvolutionStreamable.this.stream(init).limit(proceed.get());
283 }
284 };
285 }
286
287 /**
288 * Return a new {@code EvolutionStreamable} instance where all created
289 * {@code EvolutionStream}s are limited to the given number of generations.
290 *
291 * @param generations the number of generations after the created evolution
292 * streams are truncated
293 * @return a new evolution streamable object
294 * @throws IllegalArgumentException if the given {@code generations} is
295 * smaller than zero.
296 */
297 public default EvolutionStreamable<G, C> limit(final long generations) {
298 return limit(() -> Limits.byFixedGeneration(generations));
299 }
300
301 }
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