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: 617953 $ $Date: 2008-02-02 22:54:00 -0700 (Sat, 02 Feb 2008) $ 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 */ 54 public Min() { 55 n = 0; 56 value = Double.NaN; 57 } 58 59 /** 60 * @see org.apache.commons.math.stat.descriptive.StorelessUnivariateStatistic#increment(double) 61 */ 62 public void increment(final double d) { 63 if (d < value || Double.isNaN(value)) { 64 value = d; 65 } 66 n++; 67 } 68 69 /** 70 * @see org.apache.commons.math.stat.descriptive.StorelessUnivariateStatistic#clear() 71 */ 72 public void clear() { 73 value = Double.NaN; 74 n = 0; 75 } 76 77 /** 78 * @see org.apache.commons.math.stat.descriptive.StorelessUnivariateStatistic#getResult() 79 */ 80 public double getResult() { 81 return value; 82 } 83 84 /** 85 * @see org.apache.commons.math.stat.descriptive.StorelessUnivariateStatistic#getN() 86 */ 87 public long getN() { 88 return n; 89 } 90 91 /** 92 * Returns the minimum of the entries in the specified portion of 93 * the input array, or <code>Double.NaN</code> if the designated subarray 94 * is empty. 95 * <p> 96 * Throws <code>IllegalArgumentException</code> if the array is null or 97 * the array index parameters are not valid.</p> 98 * <p> 99 * <ul> 100 * <li>The result is <code>NaN</code> iff all values are <code>NaN</code> 101 * (i.e. <code>NaN</code> values have no impact on the value of the statistic).</li> 102 * <li>If any of the values equals <code>Double.NEGATIVE_INFINITY</code>, 103 * the result is <code>Double.NEGATIVE_INFINITY.</code></li> 104 * </ul> </p> 105 * 106 * @param values the input array 107 * @param begin index of the first array element to include 108 * @param length the number of elements to include 109 * @return the minimum of the values or Double.NaN if length = 0 110 * @throws IllegalArgumentException if the array is null or the array index 111 * parameters are not valid 112 */ 113 public double evaluate(final double[] values,final int begin, final int length) { 114 double min = Double.NaN; 115 if (test(values, begin, length)) { 116 min = values[begin]; 117 for (int i = begin; i < begin + length; i++) { 118 if (!Double.isNaN(values[i])) { 119 min = (min < values[i]) ? min : values[i]; 120 } 121 } 122 } 123 return min; 124 } 125 }