Reverting commit 8a35ca4f8e19b914a8503d1d5156212363cbaf10 as per Gilles request.
The work on revamping the random packages is perfoemd in the random-ravamp branch. Project: http://git-wip-us.apache.org/repos/asf/commons-math/repo Commit: http://git-wip-us.apache.org/repos/asf/commons-math/commit/e0a8ac4f Tree: http://git-wip-us.apache.org/repos/asf/commons-math/tree/e0a8ac4f Diff: http://git-wip-us.apache.org/repos/asf/commons-math/diff/e0a8ac4f Branch: refs/heads/master Commit: e0a8ac4fb5891e6760f7238027dcbb3e23e23054 Parents: 16f46dc Author: Luc Maisonobe <l...@apache.org> Authored: Sun Jan 17 11:35:24 2016 +0100 Committer: Luc Maisonobe <l...@apache.org> Committed: Sun Jan 17 11:40:27 2016 +0100 ---------------------------------------------------------------------- .../math4/random/AbstractRandomGenerator.java | 294 +++++++++++++++++++ .../random/AbstractRandomGeneratorTest.java | 39 +++ .../math4/random/TestRandomGenerator.java | 43 +++ 3 files changed, 376 insertions(+) ---------------------------------------------------------------------- http://git-wip-us.apache.org/repos/asf/commons-math/blob/e0a8ac4f/src/main/java/org/apache/commons/math4/random/AbstractRandomGenerator.java ---------------------------------------------------------------------- diff --git a/src/main/java/org/apache/commons/math4/random/AbstractRandomGenerator.java b/src/main/java/org/apache/commons/math4/random/AbstractRandomGenerator.java new file mode 100644 index 0000000..2115dbd --- /dev/null +++ b/src/main/java/org/apache/commons/math4/random/AbstractRandomGenerator.java @@ -0,0 +1,294 @@ +/* + * 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.math4.random; + +import org.apache.commons.math4.exception.NotStrictlyPositiveException; +import org.apache.commons.math4.util.FastMath; + +/** + * Abstract class implementing the {@link RandomGenerator} interface. + * Default implementations for all methods other than {@link #nextDouble()} and + * {@link #setSeed(long)} are provided. + * <p> + * All data generation methods are based on {@code code nextDouble()}. + * Concrete implementations <strong>must</strong> override + * this method and <strong>should</strong> provide better / more + * performant implementations of the other methods if the underlying PRNG + * supplies them.</p> + * + * @since 1.1 + */ +public abstract class AbstractRandomGenerator implements RandomGenerator { + + /** + * Cached random normal value. The default implementation for + * {@link #nextGaussian} generates pairs of values and this field caches the + * second value so that the full algorithm is not executed for every + * activation. The value {@code Double.NaN} signals that there is + * no cached value. Use {@link #clear} to clear the cached value. + */ + private double cachedNormalDeviate = Double.NaN; + + /** + * Construct a RandomGenerator. + */ + public AbstractRandomGenerator() { + super(); + + } + + /** + * Clears the cache used by the default implementation of + * {@link #nextGaussian}. Implementations that do not override the + * default implementation of {@code nextGaussian} should call this + * method in the implementation of {@link #setSeed(long)} + */ + public void clear() { + cachedNormalDeviate = Double.NaN; + } + + /** {@inheritDoc} */ + @Override + public void setSeed(int seed) { + setSeed((long) seed); + } + + /** {@inheritDoc} */ + @Override + public void setSeed(int[] seed) { + // the following number is the largest prime that fits in 32 bits (it is 2^32 - 5) + final long prime = 4294967291l; + + long combined = 0l; + for (int s : seed) { + combined = combined * prime + s; + } + setSeed(combined); + } + + /** + * Sets the seed of the underlying random number generator using a + * {@code long} seed. Sequences of values generated starting with the + * same seeds should be identical. + * <p> + * Implementations that do not override the default implementation of + * {@code nextGaussian} should include a call to {@link #clear} in the + * implementation of this method.</p> + * + * @param seed the seed value + */ + @Override + public abstract void setSeed(long seed); + + /** + * Generates random bytes and places them into a user-supplied + * byte array. The number of random bytes produced is equal to + * the length of the byte array. + * <p> + * The default implementation fills the array with bytes extracted from + * random integers generated using {@link #nextInt}.</p> + * + * @param bytes the non-null byte array in which to put the + * random bytes + */ + @Override + public void nextBytes(byte[] bytes) { + // Multiple 4 part of length (i.e. length with two least significant bits unset). + final int max = bytes.length & 0x7ffffffc; + + int index = 0; + // Start filling in the byte array, 4 bytes at a time. + while (index < max) { + final int random = nextInt(); + bytes[index++] = (byte) random; + bytes[index++] = (byte) (random >>> 8); + bytes[index++] = (byte) (random >>> 16); + bytes[index++] = (byte) (random >>> 24); + } + + // Fill in the remaining bytes. + if (index < bytes.length) { + int random = nextInt(); + while (true) { + bytes[index++] = (byte) random; + if (index < bytes.length) { + random >>>= 8; + } else { + break; + } + } + } + } + + /** + * Returns the next pseudorandom, uniformly distributed {@code int} + * value from this random number generator's sequence. + * All 2<font size="-1"><sup>32</sup></font> possible {@code int} values + * should be produced with (approximately) equal probability. + * <p> + * The default implementation provided here returns + * <pre> + * <code>(int) (nextDouble() * Integer.MAX_VALUE)</code> + * </pre></p> + * + * @return the next pseudorandom, uniformly distributed {@code int} + * value from this random number generator's sequence + */ + @Override + public int nextInt() { + return (int) ((2d * nextDouble() - 1d) * Integer.MAX_VALUE); + } + + /** + * Returns a pseudorandom, uniformly distributed {@code int} value + * between 0 (inclusive) and the specified value (exclusive), drawn from + * this random number generator's sequence. + * <p> + * The default implementation returns + * <pre> + * <code>(int) (nextDouble() * n</code> + * </pre></p> + * + * @param n the bound on the random number to be returned. Must be + * positive. + * @return a pseudorandom, uniformly distributed {@code int} + * value between 0 (inclusive) and n (exclusive). + * @throws NotStrictlyPositiveException if {@code n <= 0}. + */ + @Override + public int nextInt(int n) { + if (n <= 0 ) { + throw new NotStrictlyPositiveException(n); + } + int result = (int) (nextDouble() * n); + return result < n ? result : n - 1; + } + + /** + * Returns the next pseudorandom, uniformly distributed {@code long} + * value from this random number generator's sequence. All + * 2<font size="-1"><sup>64</sup></font> possible {@code long} values + * should be produced with (approximately) equal probability. + * <p> + * The default implementation returns + * <pre> + * <code>(long) (nextDouble() * Long.MAX_VALUE)</code> + * </pre></p> + * + * @return the next pseudorandom, uniformly distributed {@code long} + *value from this random number generator's sequence + */ + @Override + public long nextLong() { + return (long) ((2d * nextDouble() - 1d) * Long.MAX_VALUE); + } + + /** + * Returns the next pseudorandom, uniformly distributed + * {@code boolean} value from this random number generator's + * sequence. + * <p> + * The default implementation returns + * <pre> + * <code>nextDouble() <= 0.5</code> + * </pre></p> + * + * @return the next pseudorandom, uniformly distributed + * {@code boolean} value from this random number generator's + * sequence + */ + @Override + public boolean nextBoolean() { + return nextDouble() <= 0.5; + } + + /** + * Returns the next pseudorandom, uniformly distributed {@code float} + * value between {@code 0.0} and {@code 1.0} from this random + * number generator's sequence. + * <p> + * The default implementation returns + * <pre> + * <code>(float) nextDouble() </code> + * </pre></p> + * + * @return the next pseudorandom, uniformly distributed {@code float} + * value between {@code 0.0} and {@code 1.0} from this + * random number generator's sequence + */ + @Override + public float nextFloat() { + return (float) nextDouble(); + } + + /** + * Returns the next pseudorandom, uniformly distributed + * {@code double} value between {@code 0.0} and + * {@code 1.0} from this random number generator's sequence. + * <p> + * This method provides the underlying source of random data used by the + * other methods.</p> + * + * @return the next pseudorandom, uniformly distributed + * {@code double} value between {@code 0.0} and + * {@code 1.0} from this random number generator's sequence + */ + @Override + public abstract double nextDouble(); + + /** + * Returns the next pseudorandom, Gaussian ("normally") distributed + * {@code double} value with mean {@code 0.0} and standard + * deviation {@code 1.0} from this random number generator's sequence. + * <p> + * The default implementation uses the <em>Polar Method</em> + * due to G.E.P. Box, M.E. Muller and G. Marsaglia, as described in + * D. Knuth, <u>The Art of Computer Programming</u>, 3.4.1C.</p> + * <p> + * The algorithm generates a pair of independent random values. One of + * these is cached for reuse, so the full algorithm is not executed on each + * activation. Implementations that do not override this method should + * make sure to call {@link #clear} to clear the cached value in the + * implementation of {@link #setSeed(long)}.</p> + * + * @return the next pseudorandom, Gaussian ("normally") distributed + * {@code double} value with mean {@code 0.0} and + * standard deviation {@code 1.0} from this random number + * generator's sequence + */ + @Override + public double nextGaussian() { + if (!Double.isNaN(cachedNormalDeviate)) { + double dev = cachedNormalDeviate; + cachedNormalDeviate = Double.NaN; + return dev; + } + double v1 = 0; + double v2 = 0; + double s = 1; + while (s >=1 ) { + v1 = 2 * nextDouble() - 1; + v2 = 2 * nextDouble() - 1; + s = v1 * v1 + v2 * v2; + } + if (s != 0) { + s = FastMath.sqrt(-2 * FastMath.log(s) / s); + } + cachedNormalDeviate = v2 * s; + return v1 * s; + } +} http://git-wip-us.apache.org/repos/asf/commons-math/blob/e0a8ac4f/src/test/java/org/apache/commons/math4/random/AbstractRandomGeneratorTest.java ---------------------------------------------------------------------- diff --git a/src/test/java/org/apache/commons/math4/random/AbstractRandomGeneratorTest.java b/src/test/java/org/apache/commons/math4/random/AbstractRandomGeneratorTest.java new file mode 100644 index 0000000..79cf97d --- /dev/null +++ b/src/test/java/org/apache/commons/math4/random/AbstractRandomGeneratorTest.java @@ -0,0 +1,39 @@ +/* + * 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.math4.random; + +import org.apache.commons.math4.random.RandomGenerator; + +/** + * Test cases for the AbstractRandomGenerator class. + * + */ + +public class AbstractRandomGeneratorTest extends RandomGeneratorAbstractTest { + + public AbstractRandomGeneratorTest() { + super(); + } + + @Override + protected RandomGenerator makeGenerator() { + RandomGenerator generator = new TestRandomGenerator(); + generator.setSeed(1001); + return generator; + } + +} http://git-wip-us.apache.org/repos/asf/commons-math/blob/e0a8ac4f/src/test/java/org/apache/commons/math4/random/TestRandomGenerator.java ---------------------------------------------------------------------- diff --git a/src/test/java/org/apache/commons/math4/random/TestRandomGenerator.java b/src/test/java/org/apache/commons/math4/random/TestRandomGenerator.java new file mode 100644 index 0000000..fc820b2 --- /dev/null +++ b/src/test/java/org/apache/commons/math4/random/TestRandomGenerator.java @@ -0,0 +1,43 @@ +/* + * 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.math4.random; +import java.util.Random; + +import org.apache.commons.math4.random.AbstractRandomGenerator; + +/** + * Dummy AbstractRandomGenerator concrete subclass that just wraps a + * java.util.Random instance. Used by AbstractRandomGeneratorTest to test + * default implementations in AbstractRandomGenerator. + * + */ +public class TestRandomGenerator extends AbstractRandomGenerator { + + private Random random = new Random(); + + @Override + public void setSeed(long seed) { + clear(); + random.setSeed(seed); + } + + @Override + public double nextDouble() { + return random.nextDouble(); + } + +}
