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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    *      https://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  /*
19   * This is not the original file distributed by the Apache Software Foundation
20   * It has been modified by the Hipparchus project
21   */
22  
23  package org.hipparchus.stat.ranking;
24  
25  /**
26   * Interface representing a rank transformation.
27   */
28  public interface RankingAlgorithm {
29      /**
30       * Performs a rank transformation on the input data, returning an array
31       * of ranks.
32       * <p>
33       * Ranks should be 1-based - that is, the smallest value
34       * returned in an array of ranks should be greater than or equal to one,
35       * rather than 0. Ranks should in general take integer values, though
36       * implementations may return averages or other floating point values
37       * to resolve ties in the input data.
38       *
39       * @param data array of data to be ranked
40       * @return an array of ranks corresponding to the elements of the input array
41       */
42      double[] rank(double[] data);
43  }