1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    * 
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   * 
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  package org.apache.commons.math.stat.descriptive;
18  
19  import java.util.ArrayList;
20  import java.util.List;
21  
22  import org.apache.commons.math.TestUtils;
23  
24  import junit.framework.Test;
25  import junit.framework.TestCase;
26  import junit.framework.TestSuite;
27  
28  /**
29   * Test cases for the {@link ListUnivariateImpl} class.
30   *
31   * @version $Revision: 762087 $ $Date: 2009-04-05 10:20:18 -0400 (Sun, 05 Apr 2009) $
32   */
33  
34  public final class ListUnivariateImplTest extends TestCase {
35      
36      private double one = 1;
37      private float two = 2;
38      private int three = 3;
39  
40      private double mean = 2;
41      private double sumSq = 18;
42      private double sum = 8;
43      private double var = 0.666666666666666666667;
44      private double std = Math.sqrt(var);
45      private double n = 4;
46      private double min = 1;
47      private double max = 3;
48      private double tolerance = 10E-15;
49      
50      public ListUnivariateImplTest(String name) {
51          super(name);
52      }
53      
54      public static Test suite() {
55          TestSuite suite = new TestSuite(ListUnivariateImplTest.class);
56          suite.setName("Frequency Tests");
57          return suite;
58      }
59      
60      /** test stats */
61      public void testStats() {
62          List<Object> externalList = new ArrayList<Object>();
63          
64          DescriptiveStatistics u = new ListUnivariateImpl( externalList ); 
65  
66          assertEquals("total count",0,u.getN(),tolerance);
67          u.addValue(one);
68          u.addValue(two);
69          u.addValue(two);
70          u.addValue(three);
71          assertEquals("N",n,u.getN(),tolerance);
72          assertEquals("sum",sum,u.getSum(),tolerance);
73          assertEquals("sumsq",sumSq,u.getSumsq(),tolerance);
74          assertEquals("var",var,u.getVariance(),tolerance);
75          assertEquals("std",std,u.getStandardDeviation(),tolerance);
76          assertEquals("mean",mean,u.getMean(),tolerance);
77          assertEquals("min",min,u.getMin(),tolerance);
78          assertEquals("max",max,u.getMax(),tolerance);
79          u.clear();
80          assertEquals("total count",0,u.getN(),tolerance);    
81      }     
82      
83      public void testN0andN1Conditions() throws Exception {
84          List<Object> list = new ArrayList<Object>();
85          
86          DescriptiveStatistics u = new ListUnivariateImpl( list );
87                  
88          assertTrue("Mean of n = 0 set should be NaN", Double.isNaN( u.getMean() ) );
89          assertTrue("Standard Deviation of n = 0 set should be NaN", Double.isNaN( u.getStandardDeviation() ) );
90          assertTrue("Variance of n = 0 set should be NaN", Double.isNaN(u.getVariance() ) );
91  
92          list.add( Double.valueOf(one));
93  
94          assertTrue( "Mean of n = 1 set should be value of single item n1", u.getMean() == one);
95          assertTrue( "StdDev of n = 1 set should be zero, instead it is: " + u.getStandardDeviation(), u.getStandardDeviation() == 0);
96          assertTrue( "Variance of n = 1 set should be zero", u.getVariance() == 0);  
97      }
98      
99      public void testSkewAndKurtosis() {
100         DescriptiveStatistics u = new DescriptiveStatistics();
101         
102         double[] testArray = { 12.5, 12, 11.8, 14.2, 14.9, 14.5, 21, 8.2, 10.3, 11.3, 14.1,
103                                              9.9, 12.2, 12, 12.1, 11, 19.8, 11, 10, 8.8, 9, 12.3 };
104         for( int i = 0; i < testArray.length; i++) {
105             u.addValue( testArray[i]);
106         }
107         
108         assertEquals("mean", 12.40455, u.getMean(), 0.0001);
109         assertEquals("variance", 10.00236, u.getVariance(), 0.0001);
110         assertEquals("skewness", 1.437424, u.getSkewness(), 0.0001);
111         assertEquals("kurtosis", 2.37719, u.getKurtosis(), 0.0001);
112     }
113 
114     public void testProductAndGeometricMean() throws Exception {
115         ListUnivariateImpl u = new ListUnivariateImpl(new ArrayList<Object>());
116         u.setWindowSize(10);
117                 
118         u.addValue( 1.0 );
119         u.addValue( 2.0 );
120         u.addValue( 3.0 );
121         u.addValue( 4.0 );
122 
123         assertEquals( "Geometric mean not expected", 2.213364, u.getGeometricMean(), 0.00001 );
124 
125         // Now test rolling - StorelessDescriptiveStatistics should discount the contribution
126         // of a discarded element
127         for( int i = 0; i < 10; i++ ) {
128             u.addValue( i + 2 );
129         }
130         // Values should be (2,3,4,5,6,7,8,9,10,11)
131         
132         assertEquals( "Geometric mean not expected", 5.755931, u.getGeometricMean(), 0.00001 );
133 
134 
135     }
136     
137     /** test stats */
138     public void testSerialization() {
139         
140         DescriptiveStatistics u = new ListUnivariateImpl();
141         
142         assertEquals("total count",0,u.getN(),tolerance);
143         u.addValue(one);
144         u.addValue(two);
145         
146         DescriptiveStatistics u2 = (DescriptiveStatistics)TestUtils.serializeAndRecover(u); 
147  
148         u2.addValue(two);
149         u2.addValue(three);
150         
151         assertEquals("N",n,u2.getN(),tolerance);
152         assertEquals("sum",sum,u2.getSum(),tolerance);
153         assertEquals("sumsq",sumSq,u2.getSumsq(),tolerance);
154         assertEquals("var",var,u2.getVariance(),tolerance);
155         assertEquals("std",std,u2.getStandardDeviation(),tolerance);
156         assertEquals("mean",mean,u2.getMean(),tolerance);
157         assertEquals("min",min,u2.getMin(),tolerance);
158         assertEquals("max",max,u2.getMax(),tolerance);
159 
160         u2.clear();
161         assertEquals("total count",0,u2.getN(),tolerance);    
162     }       
163 }
164