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Diffstat (limited to 'src/main/java/org/apache/commons/math3/random/RandomGeneratorFactory.java')
-rw-r--r-- | src/main/java/org/apache/commons/math3/random/RandomGeneratorFactory.java | 118 |
1 files changed, 118 insertions, 0 deletions
diff --git a/src/main/java/org/apache/commons/math3/random/RandomGeneratorFactory.java b/src/main/java/org/apache/commons/math3/random/RandomGeneratorFactory.java new file mode 100644 index 0000000..b610b44 --- /dev/null +++ b/src/main/java/org/apache/commons/math3/random/RandomGeneratorFactory.java @@ -0,0 +1,118 @@ +/* + * 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.random; + +import org.apache.commons.math3.exception.NotStrictlyPositiveException; + +import java.util.Random; + +/** + * Utilities for creating {@link RandomGenerator} instances. + * + * @since 3.3 + */ +public class RandomGeneratorFactory { + /** Class contains only static methods. */ + private RandomGeneratorFactory() {} + + /** + * Creates a {@link RandomDataGenerator} instance that wraps a {@link Random} instance. + * + * @param rng JDK {@link Random} instance that will generate the the random data. + * @return the given RNG, wrapped in a {@link RandomGenerator}. + */ + public static RandomGenerator createRandomGenerator(final Random rng) { + return new RandomGenerator() { + /** {@inheritDoc} */ + public void setSeed(int seed) { + rng.setSeed((long) seed); + } + + /** {@inheritDoc} */ + public void setSeed(int[] seed) { + rng.setSeed(convertToLong(seed)); + } + + /** {@inheritDoc} */ + public void setSeed(long seed) { + rng.setSeed(seed); + } + + /** {@inheritDoc} */ + public void nextBytes(byte[] bytes) { + rng.nextBytes(bytes); + } + + /** {@inheritDoc} */ + public int nextInt() { + return rng.nextInt(); + } + + /** {@inheritDoc} */ + public int nextInt(int n) { + if (n <= 0) { + throw new NotStrictlyPositiveException(n); + } + return rng.nextInt(n); + } + + /** {@inheritDoc} */ + public long nextLong() { + return rng.nextLong(); + } + + /** {@inheritDoc} */ + public boolean nextBoolean() { + return rng.nextBoolean(); + } + + /** {@inheritDoc} */ + public float nextFloat() { + return rng.nextFloat(); + } + + /** {@inheritDoc} */ + public double nextDouble() { + return rng.nextDouble(); + } + + /** {@inheritDoc} */ + public double nextGaussian() { + return rng.nextGaussian(); + } + }; + } + + /** + * Converts seed from one representation to another. + * + * @param seed Original seed. + * @return the converted seed. + */ + public static long convertToLong(int[] seed) { + // The following number is the largest prime that fits + // in 32 bits (i.e. 2^32 - 5). + final long prime = 4294967291l; + + long combined = 0l; + for (int s : seed) { + combined = combined * prime + s; + } + + return combined; + } +} |