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Java > Open Source Codes > org > apache > commons > math > stat > descriptive > DescriptiveStatisticsImpl


1 /*
2  * Copyright 2003-2004 The Apache Software Foundation.
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 package org.apache.commons.math.stat.descriptive;
17
18 import java.io.Serializable JavaDoc;
19
20 import org.apache.commons.math.util.ResizableDoubleArray;
21
22 /**
23  * Default implementation of
24  * {@link org.apache.commons.math.stat.descriptive.DescriptiveStatistics}.
25  *
26  * @version $Revision$ $Date: 2005-02-26 05:11:52 -0800 (Sat, 26 Feb 2005) $
27  */
28 public class DescriptiveStatisticsImpl extends DescriptiveStatistics implements Serializable JavaDoc {
29
30     /** Serializable version identifier */
31     static final long serialVersionUID = -1868088725461221010L;
32     
33     /** hold the window size **/
34     protected int windowSize;
35     
36     /**
37      * Stored data values
38      */
39     protected ResizableDoubleArray eDA;
40
41     /**
42      * Construct a DescriptiveStatisticsImpl with infinite window
43      */
44     public DescriptiveStatisticsImpl() {
45         this(INFINITE_WINDOW);
46     }
47     
48     /**
49      * Construct a DescriptiveStatisticsImpl with finite window
50      * @param window the finite window size.
51      */
52     public DescriptiveStatisticsImpl(int window) {
53         super();
54         eDA = new ResizableDoubleArray();
55         setWindowSize(window);
56     }
57
58     /**
59      * Access the window size.
60      * @return the current window size.
61      */
62     public int getWindowSize() {
63         return windowSize;
64     }
65     
66     /**
67      * @see org.apache.commons.math.stat.descriptive.DescriptiveStatistics#getValues()
68      */
69     public double[] getValues() {
70
71         double[] copiedArray = new double[eDA.getNumElements()];
72         System.arraycopy(
73             eDA.getElements(),
74             0,
75             copiedArray,
76             0,
77             eDA.getNumElements());
78         return copiedArray;
79     }
80     
81     /**
82      * @see org.apache.commons.math.stat.descriptive.DescriptiveStatistics#getElement(int)
83      */
84     public double getElement(int index) {
85         return eDA.getElement(index);
86     }
87
88     /**
89      * @see org.apache.commons.math.stat.descriptive.DescriptiveStatistics#getN()
90      */
91     public long getN() {
92         return eDA.getNumElements();
93     }
94
95     /**
96      * @see org.apache.commons.math.stat.descriptive.DescriptiveStatistics#addValue(double)
97      */
98     public void addValue(double v) {
99         if (windowSize != INFINITE_WINDOW) {
100             if (getN() == windowSize) {
101                 eDA.addElementRolling(v);
102             } else if (getN() < windowSize) {
103                 eDA.addElement(v);
104             }
105         } else {
106             eDA.addElement(v);
107         }
108     }
109
110     /**
111      * @see org.apache.commons.math.stat.descriptive.DescriptiveStatistics#clear()
112      */
113     public void clear() {
114         eDA.clear();
115     }
116
117     /**
118      * @see org.apache.commons.math.stat.descriptive.DescriptiveStatistics#setWindowSize(int)
119      */
120     public void setWindowSize(int windowSize) {
121         if (windowSize < 1) {
122             if (windowSize != INFINITE_WINDOW) {
123                 throw new IllegalArgumentException JavaDoc("window size must be positive.");
124             }
125         }
126         
127         this.windowSize = windowSize;
128
129         // We need to check to see if we need to discard elements
130 // from the front of the array. If the windowSize is less than
131 // the current number of elements.
132 if (windowSize != INFINITE_WINDOW && windowSize < eDA.getNumElements()) {
133             eDA.discardFrontElements(eDA.getNumElements() - windowSize);
134         }
135     }
136
137     /**
138      * Apply the given statistic to this univariate collection.
139      * @param stat the statistic to apply
140      * @return the computed value of the statistic.
141      */
142     public double apply(UnivariateStatistic stat) {
143         return stat.evaluate(eDA.getValues(), eDA.start(), eDA.getNumElements());
144     }
145 }
146
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