    001    /*
    002     * Licensed to the Apache Software Foundation (ASF) under one or more
    003     * contributor license agreements.  See the NOTICE file distributed with
    004     * this work for additional information regarding copyright ownership.
    005     * The ASF licenses this file to You under the Apache License, Version 2.0
    006     * (the "License"); you may not use this file except in compliance with
    007     * the License.  You may obtain a copy of the License at
    008     *
    009     *      http://www.apache.org/licenses/LICENSE-2.0
    010     *
    011     * Unless required by applicable law or agreed to in writing, software
    012     * distributed under the License is distributed on an "AS IS" BASIS,
    013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014     * See the License for the specific language governing permissions and
    015     * limitations under the License.
    016     */
    017    package org.apache.commons.math3.stat.descriptive.summary;
    018
    019    import java.io.Serializable;
    020
    021    import org.apache.commons.math3.exception.MathIllegalArgumentException;
    022    import org.apache.commons.math3.exception.NullArgumentException;
    023    import org.apache.commons.math3.stat.descriptive.AbstractStorelessUnivariateStatistic;
    024    import org.apache.commons.math3.util.MathUtils;
    025
    026
    027    /**
    028      * Returns the sum of the available values.
    029     * <p>
    030     * If there are no values in the dataset, then 0 is returned.
    031     * If any of the values are
    032     * <code>NaN</code>, then <code>NaN</code> is returned.</p>
    033     * <p>
    034     * <strong>Note that this implementation is not synchronized.</strong> If
    035     * multiple threads access an instance of this class concurrently, and at least
    036     * one of the threads invokes the <code>increment()</code> or
    037     * <code>clear()</code> method, it must be synchronized externally.</p>
    038     *
    039     * @version $Id: Sum.java 1416643 2012-12-03 19:37:14Z tn $
    040     */
    041    public class Sum extends AbstractStorelessUnivariateStatistic implements Serializable {
    042
    043        /** Serializable version identifier */
    044        private static final long serialVersionUID = -8231831954703408316L;
    045
    046        /** */
    047        private long n;
    048
    049        /**
    050         * The currently running sum.
    051         */
    052        private double value;
    053
    054        /**
    055         * Create a Sum instance
    056         */
    057        public Sum() {
    058            n = 0;
    059            value = 0;
    060        }
    061
    062        /**
    063         * Copy constructor, creates a new {@code Sum} identical
    064         * to the {@code original}
    065         *
    066         * @param original the {@code Sum} instance to copy
    067         * @throws NullArgumentException if original is null
    068         */
    069        public Sum(Sum original) throws NullArgumentException {
    070            copy(original, this);
    071        }
    072
    073        /**
    074         * {@inheritDoc}
    075         */
    076        @Override
    077        public void increment(final double d) {
    078            value += d;
    079            n++;
    080        }
    081
    082        /**
    083         * {@inheritDoc}
    084         */
    085        @Override
    086        public double getResult() {
    087            return value;
    088        }
    089
    090        /**
    091         * {@inheritDoc}
    092         */
    093        public long getN() {
    094            return n;
    095        }
    096
    097        /**
    098         * {@inheritDoc}
    099         */
    100        @Override
    101        public void clear() {
    102            value = 0;
    103            n = 0;
    104        }
    105
    106        /**
    107         * The sum of the entries in the specified portion of
    108         * the input array, or 0 if the designated subarray
    109         * is empty.
    110         * <p>
    111         * Throws <code>MathIllegalArgumentException</code> if the array is null.</p>
    112         *
    113         * @param values the input array
    114         * @param begin index of the first array element to include
    115         * @param length the number of elements to include
    116         * @return the sum of the values or 0 if length = 0
    117         * @throws MathIllegalArgumentException if the array is null or the array index
    118         *  parameters are not valid
    119         */
    120        @Override
    121        public double evaluate(final double[] values, final int begin, final int length)
    122        throws MathIllegalArgumentException {
    123            double sum = Double.NaN;
    124            if (test(values, begin, length, true)) {
    125                sum = 0.0;
    126                for (int i = begin; i < begin + length; i++) {
    127                    sum += values[i];
    128                }
    129            }
    130            return sum;
    131        }
    132
    133        /**
    134         * The weighted sum of the entries in the specified portion of
    135         * the input array, or 0 if the designated subarray
    136         * is empty.
    137         * <p>
    138         * Throws <code>MathIllegalArgumentException</code> if any of the following are true:
    139         * <ul><li>the values array is null</li>
    140         *     <li>the weights array is null</li>
    141         *     <li>the weights array does not have the same length as the values array</li>
    142         *     <li>the weights array contains one or more infinite values</li>
    143         *     <li>the weights array contains one or more NaN values</li>
    144         *     <li>the weights array contains negative values</li>
    145         *     <li>the start and length arguments do not determine a valid array</li>
    146         * </ul></p>
    147         * <p>
    148         * Uses the formula, <pre>
    149         *    weighted sum = &Sigma;(values[i] * weights[i])
    150         * </pre></p>
    151         *
    152         * @param values the input array
    153         * @param weights the weights array
    154         * @param begin index of the first array element to include
    155         * @param length the number of elements to include
    156         * @return the sum of the values or 0 if length = 0
    157         * @throws MathIllegalArgumentException if the parameters are not valid
    158         * @since 2.1
    159         */
    160        public double evaluate(final double[] values, final double[] weights,
    161            final int begin, final int length) throws MathIllegalArgumentException {
    162            double sum = Double.NaN;
    163            if (test(values, weights, begin, length, true)) {
    164                sum = 0.0;
    165                for (int i = begin; i < begin + length; i++) {
    166                    sum += values[i] * weights[i];
    167                }
    168            }
    169            return sum;
    170        }
    171
    172        /**
    173         * The weighted sum of the entries in the the input array.
    174         * <p>
    175         * Throws <code>MathIllegalArgumentException</code> if any of the following are true:
    176         * <ul><li>the values array is null</li>
    177         *     <li>the weights array is null</li>
    178         *     <li>the weights array does not have the same length as the values array</li>
    179         *     <li>the weights array contains one or more infinite values</li>
    180         *     <li>the weights array contains one or more NaN values</li>
    181         *     <li>the weights array contains negative values</li>
    182         * </ul></p>
    183         * <p>
    184         * Uses the formula, <pre>
    185         *    weighted sum = &Sigma;(values[i] * weights[i])
    186         * </pre></p>
    187         *
    188         * @param values the input array
    189         * @param weights the weights array
    190         * @return the sum of the values or Double.NaN if length = 0
    191         * @throws MathIllegalArgumentException if the parameters are not valid
    192         * @since 2.1
    193         */
    194        public double evaluate(final double[] values, final double[] weights)
    195        throws MathIllegalArgumentException {
    196            return evaluate(values, weights, 0, values.length);
    197        }
    198
    199        /**
    200         * {@inheritDoc}
    201         */
    202        @Override
    203        public Sum copy() {
    204            Sum result = new Sum();
    205            // No try-catch or advertised exception because args are valid
    206            copy(this, result);
    207            return result;
    208        }
    209
    210        /**
    211         * Copies source to dest.
    212         * <p>Neither source nor dest can be null.</p>
    213         *
    214         * @param source Sum to copy
    215         * @param dest Sum to copy to
    216         * @throws NullArgumentException if either source or dest is null
    217         */
    218        public static void copy(Sum source, Sum dest)
    219            throws NullArgumentException {
    220            MathUtils.checkNotNull(source);
    221            MathUtils.checkNotNull(dest);
    222            dest.setData(source.getDataRef());
    223            dest.n = source.n;
    224            dest.value = source.value;
    225        }
    226
    227    }