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 */
017
018 package org.apache.commons.math.stat.ranking;
019
020 /**
021 * Strategies for handling NaN values in rank transformations.
022 * <ul>
023 * <li>MINIMAL - NaNs are treated as minimal in the ordering, equivalent to
024 * (that is, tied with) <code>Double.NEGATIVE_INFINITY</code>.</li>
025 * <li>MAXIMAL - NaNs are treated as maximal in the ordering, equivalent to
026 * <code>Double.POSITIVE_INFINITY</code></li>
027 * <li>REMOVED - NaNs are removed before the rank transform is applied</li>
028 * <li>FIXED - NaNs are left "in place," that is the rank transformation is
029 * applied to the other elements in the input array, but the NaN elements
030 * are returned unchanged.</li>
031 * </ul>
032 *
033 * @since 2.0
034 * @version $Revision: 811685 $ $Date: 2009-09-05 13:36:48 -0400 (Sat, 05 Sep 2009) $
035 */
036 public enum NaNStrategy {
037
038 /** NaNs are considered minimal in the ordering */
039 MINIMAL,
040
041 /** NaNs are considered maximal in the ordering */
042 MAXIMAL,
043
044 /** NaNs are removed before computing ranks */
045 REMOVED,
046
047 /** NaNs are left in place */
048 FIXED
049 }