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; 18 19 import org.apache.commons.math.MathRuntimeException; 20 21 /** 22 * Abstract base class for all implementations of the 23 * {@link UnivariateStatistic} interface. 24 * <p> 25 * Provides a default implementation of <code>evaluate(double[]),</code> 26 * delegating to <code>evaluate(double[], int, int)</code> in the natural way. 27 * </p> 28 * <p> 29 * Also includes a <code>test</code> method that performs generic parameter 30 * validation for the <code>evaluate</code> methods.</p> 31 * 32 * @version $Revision: 780541 $ $Date: 2009-05-31 20:47:02 -0400 (Sun, 31 May 2009) $ 33 */ 34 public abstract class AbstractUnivariateStatistic 35 implements UnivariateStatistic { 36 37 /** 38 * {@inheritDoc} 39 */ 40 public double evaluate(final double[] values) { 41 test(values, 0, 0); 42 return evaluate(values, 0, values.length); 43 } 44 45 /** 46 * {@inheritDoc} 47 */ 48 public abstract double evaluate(final double[] values, final int begin, final int length); 49 50 /** 51 * {@inheritDoc} 52 */ 53 public abstract UnivariateStatistic copy(); 54 55 /** 56 * This method is used by <code>evaluate(double[], int, int)</code> methods 57 * to verify that the input parameters designate a subarray of positive length. 58 * <p> 59 * <ul> 60 * <li>returns <code>true</code> iff the parameters designate a subarray of 61 * positive length</li> 62 * <li>throws <code>IllegalArgumentException</code> if the array is null or 63 * or the indices are invalid</li> 64 * <li>returns <code>false</li> if the array is non-null, but 65 * <code>length</code> is 0. 66 * </ul></p> 67 * 68 * @param values the input array 69 * @param begin index of the first array element to include 70 * @param length the number of elements to include 71 * @return true if the parameters are valid and designate a subarray of positive length 72 * @throws IllegalArgumentException if the indices are invalid or the array is null 73 */ 74 protected boolean test( 75 final double[] values, 76 final int begin, 77 final int length) { 78 79 if (values == null) { 80 throw MathRuntimeException.createIllegalArgumentException("input values array is null"); 81 } 82 83 if (begin < 0) { 84 throw MathRuntimeException.createIllegalArgumentException( 85 "start position cannot be negative ({0})", begin); 86 } 87 88 if (length < 0) { 89 throw MathRuntimeException.createIllegalArgumentException( 90 "length cannot be negative ({0})", length); 91 } 92 93 if (begin + length > values.length) { 94 throw MathRuntimeException.createIllegalArgumentException( 95 "subarray ends after array end"); 96 } 97 98 if (length == 0) { 99 return false; 100 } 101 102 return true; 103 104 } 105 }