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
18 package org.apache.commons.math4.legacy.stat.ranking;
19
20 /**
21 * Strategies for handling NaN values in rank transformations.
22 * <ul>
23 * <li>MINIMAL - NaNs are treated as minimal in the ordering, equivalent to
24 * (that is, tied with) <code>Double.NEGATIVE_INFINITY</code>.</li>
25 * <li>MAXIMAL - NaNs are treated as maximal in the ordering, equivalent to
26 * <code>Double.POSITIVE_INFINITY</code></li>
27 * <li>REMOVED - NaNs are removed before the rank transform is applied</li>
28 * <li>FIXED - NaNs are left "in place," that is the rank transformation is
29 * applied to the other elements in the input array, but the NaN elements
30 * are returned unchanged.</li>
31 * <li>FAILED - If any NaN is encountered in the input array, an appropriate
32 * exception is thrown</li>
33 * </ul>
34 *
35 * @since 2.0
36 */
37 public enum NaNStrategy {
38
39 /** NaNs are considered minimal in the ordering. */
40 MINIMAL,
41
42 /** NaNs are considered maximal in the ordering. */
43 MAXIMAL,
44
45 /** NaNs are removed before computing ranks. */
46 REMOVED,
47
48 /** NaNs are left in place. */
49 FIXED,
50
51 /** NaNs result in an exception.
52 * @since 3.1
53 */
54 FAILED
55 }