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.math.stat.descriptive; 018 019 import org.apache.commons.math.MathRuntimeException; 020 import org.apache.commons.math.util.MathUtils; 021 022 /** 023 * 024 * Abstract implementation of the {@link StorelessUnivariateStatistic} interface. 025 * <p> 026 * Provides default <code>evaluate()</code> and <code>incrementAll(double[])<code> 027 * implementations.</p> 028 * <p> 029 * <strong>Note that these implementations are not synchronized.</strong></p> 030 * 031 * @version $Revision: 811833 $ $Date: 2009-09-06 12:27:50 -0400 (Sun, 06 Sep 2009) $ 032 */ 033 public abstract class AbstractStorelessUnivariateStatistic 034 extends AbstractUnivariateStatistic 035 implements StorelessUnivariateStatistic { 036 037 /** 038 * This default implementation calls {@link #clear}, then invokes 039 * {@link #increment} in a loop over the the input array, and then uses 040 * {@link #getResult} to compute the return value. 041 * <p> 042 * Note that this implementation changes the internal state of the 043 * statistic. Its side effects are the same as invoking {@link #clear} and 044 * then {@link #incrementAll(double[])}.</p> 045 * <p> 046 * Implementations may override this method with a more efficient and 047 * possibly more accurate implementation that works directly with the 048 * input array.</p> 049 * <p> 050 * If the array is null, an IllegalArgumentException is thrown.</p> 051 * @param values input array 052 * @return the value of the statistic applied to the input array 053 * @see org.apache.commons.math.stat.descriptive.UnivariateStatistic#evaluate(double[]) 054 */ 055 @Override 056 public double evaluate(final double[] values) { 057 if (values == null) { 058 throw MathRuntimeException.createIllegalArgumentException("input values array is null"); 059 } 060 return evaluate(values, 0, values.length); 061 } 062 063 /** 064 * This default implementation calls {@link #clear}, then invokes 065 * {@link #increment} in a loop over the specified portion of the input 066 * array, and then uses {@link #getResult} to compute the return value. 067 * <p> 068 * Note that this implementation changes the internal state of the 069 * statistic. Its side effects are the same as invoking {@link #clear} and 070 * then {@link #incrementAll(double[], int, int)}.</p> 071 * <p> 072 * Implementations may override this method with a more efficient and 073 * possibly more accurate implementation that works directly with the 074 * input array.</p> 075 * <p> 076 * If the array is null or the index parameters are not valid, an 077 * IllegalArgumentException is thrown.</p> 078 * @param values the input array 079 * @param begin the index of the first element to include 080 * @param length the number of elements to include 081 * @return the value of the statistic applied to the included array entries 082 * @see org.apache.commons.math.stat.descriptive.UnivariateStatistic#evaluate(double[], int, int) 083 */ 084 @Override 085 public double evaluate(final double[] values, final int begin, final int length) { 086 if (test(values, begin, length)) { 087 clear(); 088 incrementAll(values, begin, length); 089 } 090 return getResult(); 091 } 092 093 /** 094 * {@inheritDoc} 095 */ 096 @Override 097 public abstract StorelessUnivariateStatistic copy(); 098 099 /** 100 * {@inheritDoc} 101 */ 102 public abstract void clear(); 103 104 /** 105 * {@inheritDoc} 106 */ 107 public abstract double getResult(); 108 109 /** 110 * {@inheritDoc} 111 */ 112 public abstract void increment(final double d); 113 114 /** 115 * This default implementation just calls {@link #increment} in a loop over 116 * the input array. 117 * <p> 118 * Throws IllegalArgumentException if the input values array is null.</p> 119 * 120 * @param values values to add 121 * @throws IllegalArgumentException if values is null 122 * @see org.apache.commons.math.stat.descriptive.StorelessUnivariateStatistic#incrementAll(double[]) 123 */ 124 public void incrementAll(double[] values) { 125 if (values == null) { 126 throw MathRuntimeException.createIllegalArgumentException("input values array is null"); 127 } 128 incrementAll(values, 0, values.length); 129 } 130 131 /** 132 * This default implementation just calls {@link #increment} in a loop over 133 * the specified portion of the input array. 134 * <p> 135 * Throws IllegalArgumentException if the input values array is null.</p> 136 * 137 * @param values array holding values to add 138 * @param begin index of the first array element to add 139 * @param length number of array elements to add 140 * @throws IllegalArgumentException if values is null 141 * @see org.apache.commons.math.stat.descriptive.StorelessUnivariateStatistic#incrementAll(double[], int, int) 142 */ 143 public void incrementAll(double[] values, int begin, int length) { 144 if (test(values, begin, length)) { 145 int k = begin + length; 146 for (int i = begin; i < k; i++) { 147 increment(values[i]); 148 } 149 } 150 } 151 152 /** 153 * Returns true iff <code>object</code> is an 154 * <code>AbstractStorelessUnivariateStatistic</code> returning the same 155 * values as this for <code>getResult()</code> and <code>getN()</code> 156 * @param object object to test equality against. 157 * @return true if object returns the same value as this 158 */ 159 @Override 160 public boolean equals(Object object) { 161 if (object == this ) { 162 return true; 163 } 164 if (object instanceof AbstractStorelessUnivariateStatistic == false) { 165 return false; 166 } 167 AbstractStorelessUnivariateStatistic stat = (AbstractStorelessUnivariateStatistic) object; 168 return MathUtils.equals(stat.getResult(), this.getResult()) && 169 MathUtils.equals(stat.getN(), this.getN()); 170 } 171 172 /** 173 * Returns hash code based on getResult() and getN() 174 * 175 * @return hash code 176 */ 177 @Override 178 public int hashCode() { 179 return 31* (31 + MathUtils.hash(getResult())) + MathUtils.hash(getN()); 180 } 181 182 }