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.math4.legacy.stat.descriptive.rank;
18
19 import org.apache.commons.math4.legacy.core.MathArrays;
20
21 /**
22 * A mid point strategy based on the average of begin and end indices.
23 * @since 3.4
24 */
25 public class CentralPivotingStrategy implements PivotingStrategy {
26 /**
27 * {@inheritDoc}
28 * This in particular picks a average of begin and end indices
29 * @return The index corresponding to a simple average of
30 * the first and the last element indices of the array slice
31 * @throws org.apache.commons.math4.legacy.exception.MathIllegalArgumentException MathIllegalArgumentException when indices exceeds range
32 */
33 @Override
34 public int pivotIndex(final double[] work, final int begin, final int end) {
35 MathArrays.verifyValues(work, begin, end - begin);
36 return begin + (end - begin)/2;
37 }
38 }