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 package org.apache.commons.math.stat.descriptive;
018
019 /**
020 * Extends the definition of {@link UnivariateStatistic} with
021 * {@link #increment} and {@link #incrementAll(double[])} methods for adding
022 * values and updating internal state.
023 * <p>
024 * This interface is designed to be used for calculating statistics that can be
025 * computed in one pass through the data without storing the full array of
026 * sample values.</p>
027 *
028 * @version $Revision: 811685 $ $Date: 2009-09-05 13:36:48 -0400 (Sat, 05 Sep 2009) $
029 */
030 public interface StorelessUnivariateStatistic extends UnivariateStatistic {
031
032 /**
033 * Updates the internal state of the statistic to reflect the addition of the new value.
034 * @param d the new value.
035 */
036 void increment(double d);
037
038 /**
039 * Updates the internal state of the statistic to reflect addition of
040 * all values in the values array. Does not clear the statistic first --
041 * i.e., the values are added <strong>incrementally</strong> to the dataset.
042 *
043 * @param values array holding the new values to add
044 * @throws IllegalArgumentException if the array is null
045 */
046 void incrementAll(double[] values);
047
048 /**
049 * Updates the internal state of the statistic to reflect addition of
050 * the values in the designated portion of the values array. Does not
051 * clear the statistic first -- i.e., the values are added
052 * <strong>incrementally</strong> to the dataset.
053 *
054 * @param values array holding the new values to add
055 * @param start the array index of the first value to add
056 * @param length the number of elements to add
057 * @throws IllegalArgumentException if the array is null or the index
058 */
059 void incrementAll(double[] values, int start, int length);
060
061 /**
062 * Returns the current value of the Statistic.
063 * @return value of the statistic, <code>Double.NaN</code> if it
064 * has been cleared or just instantiated.
065 */
066 double getResult();
067
068 /**
069 * Returns the number of values that have been added.
070 * @return the number of values.
071 */
072 long getN();
073
074 /**
075 * Clears the internal state of the Statistic
076 */
077 void clear();
078
079 /**
080 * Returns a copy of the statistic with the same internal state.
081 *
082 * @return a copy of the statistic
083 */
084 StorelessUnivariateStatistic copy();
085
086 }