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 */
017package org.apache.commons.math3.stat.descriptive;
018
019import org.apache.commons.math3.exception.util.LocalizedFormats;
020import org.apache.commons.math3.exception.MathIllegalArgumentException;
021import org.apache.commons.math3.exception.NullArgumentException;
022import org.apache.commons.math3.util.MathUtils;
023import org.apache.commons.math3.util.Precision;
024
025/**
026 *
027 * Abstract implementation of the {@link StorelessUnivariateStatistic} interface.
028 * <p>
029 * Provides default <code>evaluate()</code> and <code>incrementAll(double[])</code>
030 * implementations.</p>
031 * <p>
032 * <strong>Note that these implementations are not synchronized.</strong></p>
033 *
034 * @version $Id: AbstractStorelessUnivariateStatistic.java 1416643 2012-12-03 19:37:14Z tn $
035 */
036public abstract class AbstractStorelessUnivariateStatistic
037    extends AbstractUnivariateStatistic
038    implements StorelessUnivariateStatistic {
039
040    /**
041     * This default implementation calls {@link #clear}, then invokes
042     * {@link #increment} in a loop over the the input array, and then uses
043     * {@link #getResult} to compute the return value.
044     * <p>
045     * Note that this implementation changes the internal state of the
046     * statistic.  Its side effects are the same as invoking {@link #clear} and
047     * then {@link #incrementAll(double[])}.</p>
048     * <p>
049     * Implementations may override this method with a more efficient and
050     * possibly more accurate implementation that works directly with the
051     * input array.</p>
052     * <p>
053     * If the array is null, a MathIllegalArgumentException is thrown.</p>
054     * @param values input array
055     * @return the value of the statistic applied to the input array
056     * @throws MathIllegalArgumentException if values is null
057     * @see org.apache.commons.math3.stat.descriptive.UnivariateStatistic#evaluate(double[])
058     */
059    @Override
060    public double evaluate(final double[] values) throws MathIllegalArgumentException {
061        if (values == null) {
062            throw new NullArgumentException(LocalizedFormats.INPUT_ARRAY);
063        }
064        return evaluate(values, 0, values.length);
065    }
066
067    /**
068     * This default implementation calls {@link #clear}, then invokes
069     * {@link #increment} in a loop over the specified portion of the input
070     * array, and then uses {@link #getResult} to compute the return value.
071     * <p>
072     * Note that this implementation changes the internal state of the
073     * statistic.  Its side effects are the same as invoking {@link #clear} and
074     * then {@link #incrementAll(double[], int, int)}.</p>
075     * <p>
076     * Implementations may override this method with a more efficient and
077     * possibly more accurate implementation that works directly with the
078     * input array.</p>
079     * <p>
080     * If the array is null or the index parameters are not valid, an
081     * MathIllegalArgumentException is thrown.</p>
082     * @param values the input array
083     * @param begin the index of the first element to include
084     * @param length the number of elements to include
085     * @return the value of the statistic applied to the included array entries
086     * @throws MathIllegalArgumentException if the array is null or the indices are not valid
087     * @see org.apache.commons.math3.stat.descriptive.UnivariateStatistic#evaluate(double[], int, int)
088     */
089    @Override
090    public double evaluate(final double[] values, final int begin,
091            final int length) throws MathIllegalArgumentException {
092        if (test(values, begin, length)) {
093            clear();
094            incrementAll(values, begin, length);
095        }
096        return getResult();
097    }
098
099    /**
100     * {@inheritDoc}
101     */
102    @Override
103    public abstract StorelessUnivariateStatistic copy();
104
105    /**
106     * {@inheritDoc}
107     */
108    public abstract void clear();
109
110    /**
111     * {@inheritDoc}
112     */
113    public abstract double getResult();
114
115    /**
116     * {@inheritDoc}
117     */
118    public abstract void increment(final double d);
119
120    /**
121     * This default implementation just calls {@link #increment} in a loop over
122     * the input array.
123     * <p>
124     * Throws IllegalArgumentException if the input values array is null.</p>
125     *
126     * @param values values to add
127     * @throws MathIllegalArgumentException if values is null
128     * @see org.apache.commons.math3.stat.descriptive.StorelessUnivariateStatistic#incrementAll(double[])
129     */
130    public void incrementAll(double[] values) throws MathIllegalArgumentException {
131        if (values == null) {
132            throw new NullArgumentException(LocalizedFormats.INPUT_ARRAY);
133        }
134        incrementAll(values, 0, values.length);
135    }
136
137    /**
138     * This default implementation just calls {@link #increment} in a loop over
139     * the specified portion of the input array.
140     * <p>
141     * Throws IllegalArgumentException if the input values array is null.</p>
142     *
143     * @param values  array holding values to add
144     * @param begin   index of the first array element to add
145     * @param length  number of array elements to add
146     * @throws MathIllegalArgumentException if values is null
147     * @see org.apache.commons.math3.stat.descriptive.StorelessUnivariateStatistic#incrementAll(double[], int, int)
148     */
149    public void incrementAll(double[] values, int begin, int length) throws MathIllegalArgumentException {
150        if (test(values, begin, length)) {
151            int k = begin + length;
152            for (int i = begin; i < k; i++) {
153                increment(values[i]);
154            }
155        }
156    }
157
158    /**
159     * Returns true iff <code>object</code> is an
160     * <code>AbstractStorelessUnivariateStatistic</code> returning the same
161     * values as this for <code>getResult()</code> and <code>getN()</code>
162     * @param object object to test equality against.
163     * @return true if object returns the same value as this
164     */
165    @Override
166    public boolean equals(Object object) {
167        if (object == this ) {
168            return true;
169        }
170       if (object instanceof AbstractStorelessUnivariateStatistic == false) {
171            return false;
172        }
173        AbstractStorelessUnivariateStatistic stat = (AbstractStorelessUnivariateStatistic) object;
174        return Precision.equalsIncludingNaN(stat.getResult(), this.getResult()) &&
175               Precision.equalsIncludingNaN(stat.getN(), this.getN());
176    }
177
178    /**
179     * Returns hash code based on getResult() and getN()
180     *
181     * @return hash code
182     */
183    @Override
184    public int hashCode() {
185        return 31* (31 + MathUtils.hash(getResult())) + MathUtils.hash(getN());
186    }
187
188}