MATH-1337
Adaptor from new to old API. Class is deprecated: it is temporarily provided to allow testing of the new RNGs (in user applications) with minimal changes.
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Gilles
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/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.commons.math4.random;
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import java.io.Serializable;
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import java.io.IOException;
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import java.io.ObjectOutputStream;
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import java.io.ObjectInputStream;
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import org.apache.commons.math4.util.FastMath;
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import org.apache.commons.math4.rng.UniformRandomProvider;
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import org.apache.commons.math4.rng.RandomSource;
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/**
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* Adaptor that delegates to a {@link UniformRandomProvider} instance.
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* <p>
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* It is provided for users who wish to test the new RNG implementations
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* the <i>current</i> generators (up to version 3.6 of Commons Math) in
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* codes that require the {@code RandomGenerator} interface.
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* </p>
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* <p>
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* Applications should upgrade to use the new generators ASAP.
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* If problems are found that jeopardize the upgrade, please report them
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* on the project's
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* <a href="https://issues.apache.org/jira/browse/MATH">
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* issue tracking system</a>.
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* </p>
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*
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* <p>
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* <b>Notes:</b>
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* <ul>
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* <li>
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* The
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* {@link RandomGenerator#setSeed(int) setSeed(int)},
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* {@link RandomGenerator#setSeed(int[]) setSeed(int[])} and
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* {@link RandomGenerator#setSeed(long) setSeed(long)}
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* methods of the {@link RandomGenerator} are not part of the
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* {@link UniformRandomProvider new API}.
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* </li>
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* <li>
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* The new RNG implementations are not {@code Serializable}.
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* Use {@link RandomSource#saveState(UniformRandomProvider)}
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* instead.
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* </li>
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* <li>
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* {@link RandomGenerator#nextGaussian() nextGaussian()} is not
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* part of the {@link UniformRandomProvider new API} as it defines
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* a "post-processing" of the output of a <i>uniform</i> RNG in
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* order to follow a different distribution.
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* </li>
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* </p>
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*
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* @since 4.0
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*
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* @deprecated As of 4.0. This class is made available for testing
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* the {@link RandomSource new RNG implementations} in existing
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* applications.
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* It will be removed in the next major release.
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*/
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@Deprecated
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public final class RngAdaptor
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implements RandomGenerator,
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Serializable {
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/** Serializable version identifier. */
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private static final long serialVersionUID = 12345L;
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/** Source. */
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private final RandomSource source;
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/** Delegate. */
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private transient UniformRandomProvider delegate;
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/** Next gaussian. */
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private double nextGaussian = Double.NaN;
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/**
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* Creates a new instance.
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*
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* @param source Source of randomness.
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*/
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public RngAdaptor(RandomSource source) {
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this(source, null);
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}
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/**
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* Creates a new instance.
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*
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* @param source Source of randomness.
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* @param seed Seed. Can be {@code null}.
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*/
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public RngAdaptor(RandomSource source,
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Object seed) {
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this.source = source;
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delegate = RandomSource.create(source, seed);
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}
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/** {@inheritDoc} */
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@Override
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public void setSeed(int seed) {
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delegate = RandomSource.create(source, seed);
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clear();
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}
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/** {@inheritDoc} */
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@Override
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public void setSeed(int[] seed) {
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delegate = RandomSource.create(source, seed);
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clear();
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}
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/** {@inheritDoc} */
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@Override
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public void setSeed(long seed) {
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delegate = RandomSource.create(source, seed);
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clear();
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}
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/** {@inheritDoc} */
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@Override
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public boolean nextBoolean() {
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return delegate.nextBoolean();
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}
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/** {@inheritDoc} */
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@Override
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public void nextBytes(byte[] bytes) {
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delegate.nextBytes(bytes);
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}
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/** {@inheritDoc} */
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@Override
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public double nextDouble() {
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return delegate.nextDouble();
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}
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/** {@inheritDoc} */
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@Override
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public float nextFloat() {
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return delegate.nextFloat();
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}
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/** {@inheritDoc} */
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@Override
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public double nextGaussian() {
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final double random;
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if (Double.isNaN(nextGaussian)) {
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// generate a new pair of gaussian numbers
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final double x = nextDouble();
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final double y = nextDouble();
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final double alpha = 2 * FastMath.PI * x;
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final double r = FastMath.sqrt(-2 * FastMath.log(y));
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random = r * FastMath.cos(alpha);
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nextGaussian = r * FastMath.sin(alpha);
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} else {
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// use the second element of the pair already generated
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random = nextGaussian;
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nextGaussian = Double.NaN;
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}
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return random;
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}
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/** {@inheritDoc} */
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@Override
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public int nextInt() {
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return delegate.nextInt();
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}
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/** {@inheritDoc} */
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@Override
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public int nextInt(int n) {
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return delegate.nextInt(n);
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}
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/** {@inheritDoc} */
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@Override
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public long nextLong() {
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return delegate.nextLong();
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}
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/**
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* Clears the cache used by the default implementation of
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* {@link #nextGaussian}.
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*/
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private void clear() {
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nextGaussian = Double.NaN;
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}
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/**
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* @param out Output stream.
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* @throws IOException if an error occurs.
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*/
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private void writeObject(ObjectOutputStream out)
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throws IOException {
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// Write non-transient fields.
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out.defaultWriteObject();
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// Save current state.
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out.writeObject(RandomSource.saveState(delegate));
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}
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/**
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* @param in Input stream.
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* @throws IOException if an error occurs.
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* @throws ClassNotFoundException if an error occurs.
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*/
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private void readObject(ObjectInputStream in)
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throws IOException,
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ClassNotFoundException {
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// Read non-transient fields.
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in.defaultReadObject();
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// Recreate the "delegate" from serialized info.
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delegate = RandomSource.create(source);
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// And restore its state.
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final RandomSource.State state = (RandomSource.State) in.readObject();
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RandomSource.restoreState(delegate, state);
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}
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}
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