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 }