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.util.ArrayList;
19  import java.util.List;
20  
21  import org.apache.commons.math.TestUtils;
22  
23  import junit.framework.Test;
24  import junit.framework.TestCase;
25  import junit.framework.TestSuite;
26  
27  /**
28   * Test cases for the {@link Univariate} class.
29   *
30   * @version $Revision: 201916 $ $Date: 2005-06-26 15:25:41 -0700 (Sun, 26 Jun 2005) $
31   */
32  
33  public final class ListUnivariateImplTest extends TestCase {
34      
35      private double one = 1;
36      private float two = 2;
37      private int three = 3;
38  
39      private double mean = 2;
40      private double sumSq = 18;
41      private double sum = 8;
42      private double var = 0.666666666666666666667;
43      private double std = Math.sqrt(var);
44      private double n = 4;
45      private double min = 1;
46      private double max = 3;
47      private double skewness = 0;
48      private double kurtosis = 0.5;
49      private double tolerance = 10E-15;
50      
51      public ListUnivariateImplTest(String name) {
52          super(name);
53      }
54      
55      public void setUp() {  
56      }
57      
58      public static Test suite() {
59          TestSuite suite = new TestSuite(ListUnivariateImplTest.class);
60          suite.setName("Frequency Tests");
61          return suite;
62      }
63      
64      /** test stats */
65      public void testStats() {
66          List externalList = new ArrayList();
67          
68          DescriptiveStatistics u = new ListUnivariateImpl( externalList ); 
69  
70          assertEquals("total count",0,u.getN(),tolerance);
71          u.addValue(one);
72          u.addValue(two);
73          u.addValue(two);
74          u.addValue(three);
75          assertEquals("N",n,u.getN(),tolerance);
76          assertEquals("sum",sum,u.getSum(),tolerance);
77          assertEquals("sumsq",sumSq,u.getSumsq(),tolerance);
78          assertEquals("var",var,u.getVariance(),tolerance);
79          assertEquals("std",std,u.getStandardDeviation(),tolerance);
80          assertEquals("mean",mean,u.getMean(),tolerance);
81          assertEquals("min",min,u.getMin(),tolerance);
82          assertEquals("max",max,u.getMax(),tolerance);
83          u.clear();
84          assertEquals("total count",0,u.getN(),tolerance);    
85      }     
86      
87      public void testN0andN1Conditions() throws Exception {
88          List list = new ArrayList();
89          
90          DescriptiveStatistics u = new ListUnivariateImpl( list );
91                  
92          assertTrue("Mean of n = 0 set should be NaN", Double.isNaN( u.getMean() ) );
93          assertTrue("Standard Deviation of n = 0 set should be NaN", Double.isNaN( u.getStandardDeviation() ) );
94          assertTrue("Variance of n = 0 set should be NaN", Double.isNaN(u.getVariance() ) );
95  
96          list.add( new Double(one));
97  
98          assertTrue( "Mean of n = 1 set should be value of single item n1", u.getMean() == one);
99          assertTrue( "StdDev of n = 1 set should be zero, instead it is: " + u.getStandardDeviation(), u.getStandardDeviation() == 0);
100         assertTrue( "Variance of n = 1 set should be zero", u.getVariance() == 0);  
101     }
102     
103     public void testSkewAndKurtosis() {
104         DescriptiveStatistics u = DescriptiveStatistics.newInstance();
105         
106         double[] testArray = { 12.5, 12, 11.8, 14.2, 14.9, 14.5, 21, 8.2, 10.3, 11.3, 14.1,
107                                              9.9, 12.2, 12, 12.1, 11, 19.8, 11, 10, 8.8, 9, 12.3 };
108         for( int i = 0; i < testArray.length; i++) {
109             u.addValue( testArray[i]);
110         }
111         
112         assertEquals("mean", 12.40455, u.getMean(), 0.0001);
113         assertEquals("variance", 10.00236, u.getVariance(), 0.0001);
114         assertEquals("skewness", 1.437424, u.getSkewness(), 0.0001);
115         assertEquals("kurtosis", 2.37719, u.getKurtosis(), 0.0001);
116     }
117 
118     public void testProductAndGeometricMean() throws Exception {
119         ListUnivariateImpl u = new ListUnivariateImpl(new ArrayList());
120         u.setWindowSize(10);
121                 
122         u.addValue( 1.0 );
123         u.addValue( 2.0 );
124         u.addValue( 3.0 );
125         u.addValue( 4.0 );
126 
127         assertEquals( "Geometric mean not expected", 2.213364, u.getGeometricMean(), 0.00001 );
128 
129         // Now test rolling - StorelessDescriptiveStatistics should discount the contribution
130         // of a discarded element
131         for( int i = 0; i < 10; i++ ) {
132             u.addValue( i + 2 );
133         }
134         // Values should be (2,3,4,5,6,7,8,9,10,11)
135         
136         assertEquals( "Geometric mean not expected", 5.755931, u.getGeometricMean(), 0.00001 );
137 
138 
139     }
140     
141     /** test stats */
142     public void testSerialization() {
143         
144         DescriptiveStatistics u = null;
145         
146         try {
147             u = DescriptiveStatistics.newInstance(ListUnivariateImpl.class);
148         } catch (InstantiationException e) {
149             fail(e.getMessage());
150         } catch (IllegalAccessException e) {
151             fail(e.getMessage());
152         }
153         
154         assertEquals("total count",0,u.getN(),tolerance);
155         u.addValue(one);
156         u.addValue(two);
157         
158         DescriptiveStatistics u2 = (DescriptiveStatistics)TestUtils.serializeAndRecover(u); 
159  
160         u2.addValue(two);
161         u2.addValue(three);
162         
163         assertEquals("N",n,u2.getN(),tolerance);
164         assertEquals("sum",sum,u2.getSum(),tolerance);
165         assertEquals("sumsq",sumSq,u2.getSumsq(),tolerance);
166         assertEquals("var",var,u2.getVariance(),tolerance);
167         assertEquals("std",std,u2.getStandardDeviation(),tolerance);
168         assertEquals("mean",mean,u2.getMean(),tolerance);
169         assertEquals("min",min,u2.getMin(),tolerance);
170         assertEquals("max",max,u2.getMax(),tolerance);
171 
172         u2.clear();
173         assertEquals("total count",0,u2.getN(),tolerance);    
174     }       
175 }
176