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Diffstat (limited to 'src/main/java/org/apache/commons/math3/random/UncorrelatedRandomVectorGenerator.java')
-rw-r--r-- | src/main/java/org/apache/commons/math3/random/UncorrelatedRandomVectorGenerator.java | 91 |
1 files changed, 91 insertions, 0 deletions
diff --git a/src/main/java/org/apache/commons/math3/random/UncorrelatedRandomVectorGenerator.java b/src/main/java/org/apache/commons/math3/random/UncorrelatedRandomVectorGenerator.java new file mode 100644 index 0000000..ec38c4d --- /dev/null +++ b/src/main/java/org/apache/commons/math3/random/UncorrelatedRandomVectorGenerator.java @@ -0,0 +1,91 @@ +/* + * 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.DimensionMismatchException; + +import java.util.Arrays; + +/** + * A {@link RandomVectorGenerator} that generates vectors with uncorrelated components. Components + * of generated vectors follow (independent) Gaussian distributions, with parameters supplied in the + * constructor. + * + * @since 1.2 + */ +public class UncorrelatedRandomVectorGenerator implements RandomVectorGenerator { + + /** Underlying scalar generator. */ + private final NormalizedRandomGenerator generator; + + /** Mean vector. */ + private final double[] mean; + + /** Standard deviation vector. */ + private final double[] standardDeviation; + + /** + * Simple constructor. + * + * <p>Build an uncorrelated random vector generator from its mean and standard deviation + * vectors. + * + * @param mean expected mean values for each component + * @param standardDeviation standard deviation for each component + * @param generator underlying generator for uncorrelated normalized components + */ + public UncorrelatedRandomVectorGenerator( + double[] mean, double[] standardDeviation, NormalizedRandomGenerator generator) { + if (mean.length != standardDeviation.length) { + throw new DimensionMismatchException(mean.length, standardDeviation.length); + } + this.mean = mean.clone(); + this.standardDeviation = standardDeviation.clone(); + this.generator = generator; + } + + /** + * Simple constructor. + * + * <p>Build a null mean random and unit standard deviation uncorrelated vector generator + * + * @param dimension dimension of the vectors to generate + * @param generator underlying generator for uncorrelated normalized components + */ + public UncorrelatedRandomVectorGenerator(int dimension, NormalizedRandomGenerator generator) { + mean = new double[dimension]; + standardDeviation = new double[dimension]; + Arrays.fill(standardDeviation, 1.0); + this.generator = generator; + } + + /** + * Generate an uncorrelated random vector. + * + * @return a random vector as a newly built array of double + */ + public double[] nextVector() { + + double[] random = new double[mean.length]; + for (int i = 0; i < random.length; ++i) { + random[i] = mean[i] + standardDeviation[i] * generator.nextNormalizedDouble(); + } + + return random; + } +} |