1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 package org.apache.commons.math.stat.descriptive.rank; 18 19 import java.io.Serializable; 20 21 import org.apache.commons.math.stat.descriptive.AbstractStorelessUnivariateStatistic; 22 23 /** 24 * Returns the minimum of the available values. 25 * <p> 26 * <ul> 27 * <li>The result is <code>NaN</code> iff all values are <code>NaN</code> 28 * (i.e. <code>NaN</code> values have no impact on the value of the statistic).</li> 29 * <li>If any of the values equals <code>Double.NEGATIVE_INFINITY</code>, 30 * the result is <code>Double.NEGATIVE_INFINITY.</code></li> 31 * </ul></p> 32 * <p> 33 * <strong>Note that this implementation is not synchronized.</strong> If 34 * multiple threads access an instance of this class concurrently, and at least 35 * one of the threads invokes the <code>increment()</code> or 36 * <code>clear()</code> method, it must be synchronized externally.</p> 37 * 38 * @version $Revision: 1006299 $ $Date: 2010-10-10 16:47:17 +0200 (dim. 10 oct. 2010) $ 39 */ 40 public class Min extends AbstractStorelessUnivariateStatistic implements Serializable { 41 42 /** Serializable version identifier */ 43 private static final long serialVersionUID = -2941995784909003131L; 44 45 /**Number of values that have been added */ 46 private long n; 47 48 /**Current value of the statistic */ 49 private double value; 50 51 /** 52 * Create a Min instance 53 */ Min()54 public Min() { 55 n = 0; 56 value = Double.NaN; 57 } 58 59 /** 60 * Copy constructor, creates a new {@code Min} identical 61 * to the {@code original} 62 * 63 * @param original the {@code Min} instance to copy 64 */ Min(Min original)65 public Min(Min original) { 66 copy(original, this); 67 } 68 69 /** 70 * {@inheritDoc} 71 */ 72 @Override increment(final double d)73 public void increment(final double d) { 74 if (d < value || Double.isNaN(value)) { 75 value = d; 76 } 77 n++; 78 } 79 80 /** 81 * {@inheritDoc} 82 */ 83 @Override clear()84 public void clear() { 85 value = Double.NaN; 86 n = 0; 87 } 88 89 /** 90 * {@inheritDoc} 91 */ 92 @Override getResult()93 public double getResult() { 94 return value; 95 } 96 97 /** 98 * {@inheritDoc} 99 */ getN()100 public long getN() { 101 return n; 102 } 103 104 /** 105 * Returns the minimum of the entries in the specified portion of 106 * the input array, or <code>Double.NaN</code> if the designated subarray 107 * is empty. 108 * <p> 109 * Throws <code>IllegalArgumentException</code> if the array is null or 110 * the array index parameters are not valid.</p> 111 * <p> 112 * <ul> 113 * <li>The result is <code>NaN</code> iff all values are <code>NaN</code> 114 * (i.e. <code>NaN</code> values have no impact on the value of the statistic).</li> 115 * <li>If any of the values equals <code>Double.NEGATIVE_INFINITY</code>, 116 * the result is <code>Double.NEGATIVE_INFINITY.</code></li> 117 * </ul> </p> 118 * 119 * @param values the input array 120 * @param begin index of the first array element to include 121 * @param length the number of elements to include 122 * @return the minimum of the values or Double.NaN if length = 0 123 * @throws IllegalArgumentException if the array is null or the array index 124 * parameters are not valid 125 */ 126 @Override evaluate(final double[] values,final int begin, final int length)127 public double evaluate(final double[] values,final int begin, final int length) { 128 double min = Double.NaN; 129 if (test(values, begin, length)) { 130 min = values[begin]; 131 for (int i = begin; i < begin + length; i++) { 132 if (!Double.isNaN(values[i])) { 133 min = (min < values[i]) ? min : values[i]; 134 } 135 } 136 } 137 return min; 138 } 139 140 /** 141 * {@inheritDoc} 142 */ 143 @Override copy()144 public Min copy() { 145 Min result = new Min(); 146 copy(this, result); 147 return result; 148 } 149 150 /** 151 * Copies source to dest. 152 * <p>Neither source nor dest can be null.</p> 153 * 154 * @param source Min to copy 155 * @param dest Min to copy to 156 * @throws NullPointerException if either source or dest is null 157 */ copy(Min source, Min dest)158 public static void copy(Min source, Min dest) { 159 dest.setData(source.getDataRef()); 160 dest.n = source.n; 161 dest.value = source.value; 162 } 163 } 164