    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.math3.stat.ranking;
    019
    020    /**
    021     * Interface representing a rank transformation.
    022     *
    023     * @since 2.0
    024     * @version $Id: RankingAlgorithm.java 1416643 2012-12-03 19:37:14Z tn $
    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    }