| /* |
| * 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.legacy.stat.descriptive.summary; |
| |
| import java.io.Serializable; |
| |
| import org.apache.commons.math4.legacy.exception.MathIllegalArgumentException; |
| import org.apache.commons.math4.legacy.exception.NullArgumentException; |
| import org.apache.commons.math4.legacy.stat.descriptive.AbstractStorelessUnivariateStatistic; |
| import org.apache.commons.math4.legacy.stat.descriptive.WeightedEvaluation; |
| import org.apache.commons.math4.core.jdkmath.JdkMath; |
| import org.apache.commons.math4.legacy.core.MathArrays; |
| |
| /** |
| * Returns the product of the available values. |
| * <p> |
| * If there are no values in the dataset, then 1 is returned. |
| * If any of the values are |
| * <code>NaN</code>, then <code>NaN</code> is returned.</p> |
| * <p> |
| * <strong>Note that this implementation is not synchronized.</strong> If |
| * multiple threads access an instance of this class concurrently, and at least |
| * one of the threads invokes the <code>increment()</code> or |
| * <code>clear()</code> method, it must be synchronized externally.</p> |
| */ |
| public class Product extends AbstractStorelessUnivariateStatistic implements Serializable, WeightedEvaluation { |
| |
| /** Serializable version identifier. */ |
| private static final long serialVersionUID = 20150412L; |
| |
| /**The number of values that have been added. */ |
| private long n; |
| |
| /** |
| * The current Running Product. |
| */ |
| private double value; |
| |
| /** |
| * Create a Product instance. |
| */ |
| public Product() { |
| n = 0; |
| value = 1; |
| } |
| |
| /** |
| * Copy constructor, creates a new {@code Product} identical |
| * to the {@code original}. |
| * |
| * @param original the {@code Product} instance to copy |
| * @throws NullArgumentException if original is null |
| */ |
| public Product(Product original) throws NullArgumentException { |
| copy(original, this); |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public void increment(final double d) { |
| value *= d; |
| n++; |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public double getResult() { |
| return value; |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public long getN() { |
| return n; |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public void clear() { |
| value = 1; |
| n = 0; |
| } |
| |
| /** |
| * Returns the product of the entries in the specified portion of |
| * the input array, or <code>Double.NaN</code> if the designated subarray |
| * is empty. |
| * <p> |
| * Throws <code>MathIllegalArgumentException</code> if the array is null.</p> |
| * |
| * @param values the input array |
| * @param begin index of the first array element to include |
| * @param length the number of elements to include |
| * @return the product of the values or 1 if length = 0 |
| * @throws MathIllegalArgumentException if the array is null or the array index |
| * parameters are not valid |
| */ |
| @Override |
| public double evaluate(final double[] values, final int begin, final int length) |
| throws MathIllegalArgumentException { |
| double product = Double.NaN; |
| if (MathArrays.verifyValues(values, begin, length, true)) { |
| product = 1.0; |
| for (int i = begin; i < begin + length; i++) { |
| product *= values[i]; |
| } |
| } |
| return product; |
| } |
| |
| /** |
| * <p>Returns the weighted product of the entries in the specified portion of |
| * the input array, or <code>Double.NaN</code> if the designated subarray |
| * is empty.</p> |
| * |
| * <p>Throws <code>MathIllegalArgumentException</code> if any of the following are true: |
| * <ul><li>the values array is null</li> |
| * <li>the weights array is null</li> |
| * <li>the weights array does not have the same length as the values array</li> |
| * <li>the weights array contains one or more infinite values</li> |
| * <li>the weights array contains one or more NaN values</li> |
| * <li>the weights array contains negative values</li> |
| * <li>the start and length arguments do not determine a valid array</li> |
| * </ul> |
| * |
| * <p>Uses the formula, <div style="white-space: pre"><code> |
| * weighted product = ∏values[i]<sup>weights[i]</sup> |
| * </code></div> |
| * that is, the weights are applied as exponents when computing the weighted product. |
| * |
| * @param values the input array |
| * @param weights the weights array |
| * @param begin index of the first array element to include |
| * @param length the number of elements to include |
| * @return the product of the values or 1 if length = 0 |
| * @throws MathIllegalArgumentException if the parameters are not valid |
| * @since 2.1 |
| */ |
| @Override |
| public double evaluate(final double[] values, final double[] weights, |
| final int begin, final int length) throws MathIllegalArgumentException { |
| double product = Double.NaN; |
| if (MathArrays.verifyValues(values, weights, begin, length, true)) { |
| product = 1.0; |
| for (int i = begin; i < begin + length; i++) { |
| product *= JdkMath.pow(values[i], weights[i]); |
| } |
| } |
| return product; |
| } |
| |
| /** |
| * <p>Returns the weighted product of the entries in the input array.</p> |
| * |
| * <p>Throws <code>MathIllegalArgumentException</code> if any of the following are true: |
| * <ul><li>the values array is null</li> |
| * <li>the weights array is null</li> |
| * <li>the weights array does not have the same length as the values array</li> |
| * <li>the weights array contains one or more infinite values</li> |
| * <li>the weights array contains one or more NaN values</li> |
| * <li>the weights array contains negative values</li> |
| * </ul> |
| * |
| * <p>Uses the formula, |
| * <div style="white-space: pre"><code> |
| * weighted product = ∏values[i]<sup>weights[i]</sup> |
| * </code></div> |
| * that is, the weights are applied as exponents when computing the weighted product. |
| * |
| * @param values the input array |
| * @param weights the weights array |
| * @return the product of the values or Double.NaN if length = 0 |
| * @throws MathIllegalArgumentException if the parameters are not valid |
| * @since 2.1 |
| */ |
| @Override |
| public double evaluate(final double[] values, final double[] weights) throws MathIllegalArgumentException { |
| return evaluate(values, weights, 0, values.length); |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public Product copy() { |
| Product result = new Product(); |
| // No try-catch or advertised exception because args are valid |
| copy(this, result); |
| return result; |
| } |
| |
| /** |
| * Copies source to dest. |
| * <p>Neither source nor dest can be null.</p> |
| * |
| * @param source Product to copy |
| * @param dest Product to copy to |
| * @throws NullArgumentException if either source or dest is null |
| */ |
| public static void copy(Product source, Product dest) |
| throws NullArgumentException { |
| NullArgumentException.check(source); |
| NullArgumentException.check(dest); |
| dest.n = source.n; |
| dest.value = source.value; |
| } |
| |
| } |