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 */ 017package org.apache.commons.math4.legacy.stat.descriptive.rank; 018 019import org.apache.commons.math4.legacy.core.MathArrays; 020 021/** 022 * A mid point strategy based on the average of begin and end indices. 023 * @since 3.4 024 */ 025public class CentralPivotingStrategy implements PivotingStrategy { 026 /** 027 * {@inheritDoc} 028 * This in particular picks a average of begin and end indices 029 * @return The index corresponding to a simple average of 030 * the first and the last element indices of the array slice 031 * @throws org.apache.commons.math4.legacy.exception.MathIllegalArgumentException MathIllegalArgumentException when indices exceeds range 032 */ 033 @Override 034 public int pivotIndex(final double[] work, final int begin, final int end) { 035 MathArrays.verifyValues(work, begin, end - begin); 036 return begin + (end - begin)/2; 037 } 038}