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   * Interface representing a rank transformation.
22   * 
23   * @since 2.0
24   * @version $Revision: 799857 $ $Date: 2009-08-01 09:07:12 -0400 (Sat, 01 Aug 2009) $
25   */
26  public interface RankingAlgorithm {
27      /**
28       * <p>Performs a rank transformation on the input data, returning an array
29       * of ranks.</p>
30       * 
31       * <p>Ranks should be 1-based - that is, the smallest value
32       * returned in an array of ranks should be greater than or equal to one,
33       * rather than 0. Ranks should in general take integer values, though
34       * implementations may return averages or other floating point values
35       * to resolve ties in the input data.</p>
36       * 
37       * @param data array of data to be ranked
38       * @return an array of ranks corresponding to the elements of the input array
39       */
40      double[] rank (double[] data);
41  }