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 */
017package org.apache.commons.math3.stat.descriptive;
018
019import org.apache.commons.math3.exception.MathIllegalArgumentException;
020
021/**
022 * Extends the definition of {@link UnivariateStatistic} with
023 * {@link #increment} and {@link #incrementAll(double[])} methods for adding
024 * values and updating internal state.
025 * <p>
026 * This interface is designed to be used for calculating statistics that can be
027 * computed in one pass through the data without storing the full array of
028 * sample values.</p>
029 *
030 * @version $Id: StorelessUnivariateStatistic.java 1416643 2012-12-03 19:37:14Z tn $
031 */
032public interface StorelessUnivariateStatistic extends UnivariateStatistic {
033
034    /**
035     * Updates the internal state of the statistic to reflect the addition of the new value.
036     * @param d  the new value.
037     */
038    void increment(double d);
039
040    /**
041     * Updates the internal state of the statistic to reflect addition of
042     * all values in the values array.  Does not clear the statistic first --
043     * i.e., the values are added <strong>incrementally</strong> to the dataset.
044     *
045     * @param values  array holding the new values to add
046     * @throws MathIllegalArgumentException if the array is null
047     */
048    void incrementAll(double[] values) throws MathIllegalArgumentException;
049
050    /**
051     * Updates the internal state of the statistic to reflect addition of
052     * the values in the designated portion of the values array.  Does not
053     * clear the statistic first -- i.e., the values are added
054     * <strong>incrementally</strong> to the dataset.
055     *
056     * @param values  array holding the new values to add
057     * @param start  the array index of the first value to add
058     * @param length  the number of elements to add
059     * @throws MathIllegalArgumentException if the array is null or the index
060     */
061    void incrementAll(double[] values, int start, int length) throws MathIllegalArgumentException;
062
063    /**
064     * Returns the current value of the Statistic.
065     * @return value of the statistic, <code>Double.NaN</code> if it
066     * has been cleared or just instantiated.
067     */
068    double getResult();
069
070    /**
071     * Returns the number of values that have been added.
072     * @return the number of values.
073     */
074    long getN();
075
076    /**
077     * Clears the internal state of the Statistic
078     */
079    void clear();
080
081    /**
082     * Returns a copy of the statistic with the same internal state.
083     *
084     * @return a copy of the statistic
085     */
086    StorelessUnivariateStatistic copy();
087
088}