Check-in commons-math 3.6.1 am: 1354beaf45

Original change: https://android-review.googlesource.com/c/platform/external/apache-commons-math/+/2702413

Change-Id: I4990b1b31e5dd9596f208d93dd22cc8d5e470689
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>

1 files changed, 55 insertions, 0 deletions

diff --git a/src/main/java/org/apache/commons/math3/genetics/RandomKeyMutation.java b/src/main/java/org/apache/commons/math3/genetics/RandomKeyMutation.java
new file mode 100644
index 0000000..6d1512a
--- /dev/null
+++ b/src/main/java/org/apache/commons/math3/genetics/RandomKeyMutation.java
@@ -0,0 +1,55 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.commons.math3.genetics;
+
+import org.apache.commons.math3.exception.MathIllegalArgumentException;
+import org.apache.commons.math3.exception.util.LocalizedFormats;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Mutation operator for {@link RandomKey}s. Changes a randomly chosen element of the array
+ * representation to a random value uniformly distributed in [0,1].
+ *
+ * @since 2.0
+ */
+public class RandomKeyMutation implements MutationPolicy {
+
+    /**
+     * {@inheritDoc}
+     *
+     * @throws MathIllegalArgumentException if <code>original</code> is not a {@link RandomKey}
+     *     instance
+     */
+    public Chromosome mutate(final Chromosome original) throws MathIllegalArgumentException {
+        if (!(original instanceof RandomKey<?>)) {
+            throw new MathIllegalArgumentException(
+                    LocalizedFormats.RANDOMKEY_MUTATION_WRONG_CLASS,
+                    original.getClass().getSimpleName());
+        }
+
+        RandomKey<?> originalRk = (RandomKey<?>) original;
+        List<Double> repr = originalRk.getRepresentation();
+        int rInd = GeneticAlgorithm.getRandomGenerator().nextInt(repr.size());
+
+        List<Double> newRepr = new ArrayList<Double>(repr);
+        newRepr.set(rInd, GeneticAlgorithm.getRandomGenerator().nextDouble());
+
+        return originalRk.newFixedLengthChromosome(newRepr);
+    }
+}