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;
018
019 import org.apache.commons.math3.exception.util.LocalizedFormats;
020 import org.apache.commons.math3.exception.MathIllegalArgumentException;
021 import org.apache.commons.math3.exception.NullArgumentException;
022 import org.apache.commons.math3.util.MathUtils;
023 import 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 */
036 public 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 }