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 package org.apache.commons.statistics.ranking; 18 19 import java.util.function.UnaryOperator; 20 21 /** 22 * Interface representing a rank transformation. 23 * 24 * @since 1.1 25 */ 26 @FunctionalInterface 27 public interface RankingAlgorithm extends UnaryOperator<double[]> { 28 /** 29 * <p>Performs a rank transformation on the input data, returning an array of 30 * ranks. 31 * 32 * <p>Ranks should be 1-based: the smallest value returned in an array of ranks 33 * should be greater than or equal to one, rather than 0. Ranks should in 34 * general take integer values, though implementations may return averages or 35 * other floating point values to resolve ties in the input data. 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 @Override 41 double[] apply(double[] data); 42 }