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 * Interface representing a rank transformation.
022 *
023 * @since 2.0
024 * @version $Revision: 811685 $ $Date: 2009-09-05 19:36:48 +0200 (sam. 05 sept. 2009) $
025 */
026 public interface RankingAlgorithm {
027 /**
028 * <p>Performs a rank transformation on the input data, returning an array
029 * of ranks.</p>
030 *
031 * <p>Ranks should be 1-based - that is, the smallest value
032 * returned in an array of ranks should be greater than or equal to one,
033 * rather than 0. Ranks should in general take integer values, though
034 * implementations may return averages or other floating point values
035 * to resolve ties in the input data.</p>
036 *
037 * @param data array of data to be ranked
038 * @return an array of ranks corresponding to the elements of the input array
039 */
040 double[] rank (double[] data);
041 }