View Javadoc

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.math.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   * </ul>
32   *
33   * @since 2.0
34   * @version $Revision: 799857 $ $Date: 2009-08-01 09:07:12 -0400 (Sat, 01 Aug 2009) $
35   */
36  public enum NaNStrategy {
37      
38      /** NaNs are considered minimal in the ordering */
39      MINIMAL,
40      
41      /** NaNs are considered maximal in the ordering */
42      MAXIMAL,
43      
44      /** NaNs are removed before computing ranks */
45      REMOVED,
46      
47      /** NaNs are left in place */
48      FIXED
49  }