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erans pushed a commit to branch feature__MATH-1563__genetic_algorithm
in repository https://gitbox.apache.org/repos/asf/commons-math.git
commit 383256f8cfcbf1de70f93a1d1ea0e7c972812af0
Author: Gilles Sadowski <gillese...@gmail.com>
AuthorDate: Sun Jun 12 02:41:56 2022 +0200
MATH-1618: Make "stopping condition" a "BiPredicate".
Second argument is the generation count (as determined by the caller).
---
.../ga/mathfunctions/MathFunctionOptimizer2.java | 4 ++--
.../commons/math4/ga2/GeneticAlgorithmFactory.java | 13 +++++------
.../commons/math4/ga2/stop/UnchangedFitness.java | 27 +++++++++++++++-------
3 files changed, 27 insertions(+), 17 deletions(-)
diff --git
a/commons-math-examples/examples-ga/examples-ga-math-functions/src/main/java/org/apache/commons/math4/examples/ga/mathfunctions/MathFunctionOptimizer2.java
b/commons-math-examples/examples-ga/examples-ga-math-functions/src/main/java/org/apache/commons/math4/examples/ga/mathfunctions/MathFunctionOptimizer2.java
index 96ea5087b..ac128d89e 100644
---
a/commons-math-examples/examples-ga/examples-ga-math-functions/src/main/java/org/apache/commons/math4/examples/ga/mathfunctions/MathFunctionOptimizer2.java
+++
b/commons-math-examples/examples-ga/examples-ga-math-functions/src/main/java/org/apache/commons/math4/examples/ga/mathfunctions/MathFunctionOptimizer2.java
@@ -23,7 +23,7 @@ import java.util.HashMap;
import java.util.List;
import java.util.function.Function;
import java.util.function.ToDoubleFunction;
-import java.util.function.Predicate;
+import java.util.function.BiPredicate;
import java.util.concurrent.Executors;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Callable;
@@ -100,7 +100,7 @@ public final class MathFunctionOptimizer2 {
};
// Stopping condition (not thread-safe).
- final Predicate<Population<Chromosome, Coordinates>> stop =
+ final BiPredicate<Population<Chromosome, Coordinates>, Integer> stop =
new UnchangedFitness(UnchangedFitness.Type.BEST,
numGeneration);
diff --git
a/commons-math-ga2/src/main/java/org/apache/commons/math4/ga2/GeneticAlgorithmFactory.java
b/commons-math-ga2/src/main/java/org/apache/commons/math4/ga2/GeneticAlgorithmFactory.java
index 40ec98249..9386e5617 100644
---
a/commons-math-ga2/src/main/java/org/apache/commons/math4/ga2/GeneticAlgorithmFactory.java
+++
b/commons-math-ga2/src/main/java/org/apache/commons/math4/ga2/GeneticAlgorithmFactory.java
@@ -23,7 +23,7 @@ import java.util.ArrayList;
import java.util.Map;
import java.util.concurrent.Callable;
import java.util.function.Function;
-import java.util.function.Predicate;
+import java.util.function.BiPredicate;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.commons.rng.simple.RandomSource;
@@ -43,7 +43,7 @@ public final class GeneticAlgorithmFactory<G, P> implements
Callable<Population<
/** Genotype to phenotype converter. */
private final Function<G, P> decoder;
/** Criterion for stopping the evolution. */
- private final Predicate<Population<G, P>> stop;
+ private final BiPredicate<Population<G, P>, Integer> stop;
/** Fitness calculator. */
private final FitnessService<G, P> fitness;
/** Chromosome selector. */
@@ -71,7 +71,7 @@ public final class GeneticAlgorithmFactory<G, P> implements
Callable<Population<
*/
private GeneticAlgorithmFactory(Collection<G> init,
Function<G, P> decoder,
- Predicate<Population<G, P>> stop,
+ BiPredicate<Population<G, P>, Integer>
stop,
FitnessService<G, P> fitness,
Selection<G, P> selection,
Map<GeneticOperator<G>, ApplicationRate>
operators,
@@ -107,7 +107,7 @@ public final class GeneticAlgorithmFactory<G, P> implements
Callable<Population<
*/
public static <G, P> Callable<Population<G, P>> create(Collection<G> init,
Function<G, P>
decoder,
-
Predicate<Population<G, P>> stop,
+
BiPredicate<Population<G, P>, Integer> stop,
FitnessService<G,
P> fitness,
Selection<G, P>
selection,
Map<GeneticOperator<G>, ApplicationRate> operators,
@@ -147,7 +147,7 @@ public final class GeneticAlgorithmFactory<G, P> implements
Callable<Population<
ChromosomeFactory<G> initFactory,
int populationSize,
Function<G, P>
decoder,
-
Predicate<Population<G, P>> stop,
+
BiPredicate<Population<G, P>, Integer> stop,
FitnessService<G,
P> fitness,
Selection<G, P>
selection,
Map<GeneticOperator<G>, ApplicationRate> operators,
@@ -181,8 +181,7 @@ public final class GeneticAlgorithmFactory<G, P> implements
Callable<Population<
currentGen.add(init);
final UniformRandomProvider rng = random.create();
- while (!stop.test(currentGen)) {
- ++generation;
+ while (!stop.test(currentGen, ++generation)) {
final Population<G, P> nextGen = new Population<>(popSize,
decoder, fitness);
applyElitism(currentGen, nextGen);
diff --git
a/commons-math-ga2/src/main/java/org/apache/commons/math4/ga2/stop/UnchangedFitness.java
b/commons-math-ga2/src/main/java/org/apache/commons/math4/ga2/stop/UnchangedFitness.java
index c261c434f..228abd9aa 100644
---
a/commons-math-ga2/src/main/java/org/apache/commons/math4/ga2/stop/UnchangedFitness.java
+++
b/commons-math-ga2/src/main/java/org/apache/commons/math4/ga2/stop/UnchangedFitness.java
@@ -18,25 +18,30 @@ package org.apache.commons.math4.ga2.stop;
import java.util.Map;
import java.util.function.ToDoubleFunction;
-import java.util.function.Predicate;
+import java.util.function.BiPredicate;
import org.apache.commons.math4.ga2.Population;
/**
* Criterion for asserting convergence of a population.
- * Note: Class is <em>not</em> thread-safe.
+ * Notes:
+ * <ul>
+ * <li>Class is <em>not</em> thread-safe.</li>
+ * <li>A <em>new</em> instance must created for each GA run (otherwise
+ * an {@link IllegalStateException} will be thrown).</li>
+ * </ul>
*
* @param <G> Genotype.
* @param <P> Phenotype.
*/
-public class UnchangedFitness<G, P> implements Predicate<Population<G, P>> {
+public class UnchangedFitness<G, P> implements BiPredicate<Population<G, P>,
Integer> {
/** Function that computes the reference value. */
private final ToDoubleFunction<Population<G, P>> calculator;
/** Number of generations during which no change has happened. */
private final int maxGenerations;
/** Value for previous population. */
private double previousFitness = Double.NaN;
- /** Number of generations without changes. */
- private int generations = 0;
+ /** Generation at which the last change has occurred. */
+ private int updatedGeneration = 0;
/** What needs to be unchanged. */
public enum Type {
@@ -71,14 +76,20 @@ public class UnchangedFitness<G, P> implements
Predicate<Population<G, P>> {
/** {@inheritDoc} */
@Override
- public boolean test(Population<G, P> population) {
+ public boolean test(Population<G, P> population,
+ Integer generationCounter) {
+ final int genDiff = generationCounter - updatedGeneration;
+ if (genDiff < 0) {
+ throw new IllegalStateException("Incorrect usage");
+ }
+
final double fitness = calculator.applyAsDouble(population);
if (fitness == previousFitness) {
- if (++generations > maxGenerations) {
+ if (genDiff > maxGenerations) {
return true;
}
} else {
- generations = 0;
+ updatedGeneration = generationCounter;
previousFitness = fitness;
}
