/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You under the Apache License, Version 2.0
    * (the "License"); you may not use this file except in compliance with
    * the License.  You may obtain a copy of the License at
    *
    *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.commons.math4.legacy.stat.inference;
  
  
  import org.apache.commons.math4.legacy.exception.NullArgumentException;
  import org.apache.commons.math4.legacy.exception.NumberIsTooSmallException;
  import org.apache.commons.math4.legacy.exception.OutOfRangeException;
  import org.apache.commons.math4.legacy.stat.descriptive.SummaryStatistics;
  import org.junit.Assert;
  import org.junit.Before;
  import org.junit.Test;
  
  /**
   * Test cases for the TTestImpl class.
   *
   */
  public class TTestTest {
  
      protected TTest testStatistic = new TTest();
  
      private double[] tooShortObs = { 1.0 };
      private double[] emptyObs = {};
      private SummaryStatistics emptyStats = new SummaryStatistics();
      private SummaryStatistics tooShortStats = null;
  
      @Before
      public void setUp() {
          tooShortStats = new SummaryStatistics();
          tooShortStats.addValue(0d);
      }
  
      @Test
      public void testOneSampleT() {
          double[] observed =
              {93.0, 103.0, 95.0, 101.0, 91.0, 105.0, 96.0, 94.0, 101.0,  88.0, 98.0, 94.0, 101.0, 92.0, 95.0 };
          double mu = 100.0;
          SummaryStatistics sampleStats = null;
          sampleStats = new SummaryStatistics();
          for (int i = 0; i < observed.length; i++) {
              sampleStats.addValue(observed[i]);
          }
  
          // Target comparison values computed using R version 1.8.1 (Linux version)
          Assert.assertEquals("t statistic",  -2.81976445346,
                  testStatistic.t(mu, observed), 10E-10);
          Assert.assertEquals("t statistic",  -2.81976445346,
                  testStatistic.t(mu, sampleStats), 10E-10);
          Assert.assertEquals("p value", 0.0136390585873,
                  testStatistic.tTest(mu, observed), 10E-10);
          Assert.assertEquals("p value", 0.0136390585873,
                  testStatistic.tTest(mu, sampleStats), 10E-10);
  
          try {
              testStatistic.t(mu, (double[]) null);
              Assert.fail("arguments too short, NullArgumentException expected");
          } catch (NullArgumentException ex) {
              // expected
          }
  
          try {
              testStatistic.t(mu, (SummaryStatistics) null);
              Assert.fail("arguments too short, NullArgumentException expected");
          } catch (NullArgumentException ex) {
              // expected
          }
  
          try {
              testStatistic.t(mu, emptyObs);
              Assert.fail("arguments too short, NumberIsTooSmallException expected");
          } catch (NumberIsTooSmallException ex) {
              // expected
          }
  
          try {
              testStatistic.t(mu, emptyStats);
              Assert.fail("arguments too short, NumberIsTooSmallException expected");
          } catch (NumberIsTooSmallException ex) {
              // expected
          }
  
          try {
              testStatistic.t(mu, tooShortObs);
              Assert.fail("insufficient data to compute t statistic, NumberIsTooSmallException expected");
          } catch (NumberIsTooSmallException ex) {
             // expected
         }
         try {
             testStatistic.tTest(mu, tooShortObs);
             Assert.fail("insufficient data to perform t test, NumberIsTooSmallException expected");
         } catch (NumberIsTooSmallException ex) {
            // expected
         }
 
         try {
             testStatistic.t(mu, tooShortStats);
             Assert.fail("insufficient data to compute t statistic, NumberIsTooSmallException expected");
         } catch (NumberIsTooSmallException ex) {
             // expected
         }
         try {
             testStatistic.tTest(mu, tooShortStats);
             Assert.fail("insufficient data to perform t test, NumberIsTooSmallException expected");
         } catch (NumberIsTooSmallException ex) {
             // expected
         }
     }
 
     @Test
     public void testOneSampleTTest() {
         double[] oneSidedP =
             {2d, 0d, 6d, 6d, 3d, 3d, 2d, 3d, -6d, 6d, 6d, 6d, 3d, 0d, 1d, 1d, 0d, 2d, 3d, 3d };
         SummaryStatistics oneSidedPStats = new SummaryStatistics();
         for (int i = 0; i < oneSidedP.length; i++) {
             oneSidedPStats.addValue(oneSidedP[i]);
         }
         // Target comparison values computed using R version 1.8.1 (Linux version)
         Assert.assertEquals("one sample t stat", 3.86485535541,
                 testStatistic.t(0d, oneSidedP), 10E-10);
         Assert.assertEquals("one sample t stat", 3.86485535541,
                 testStatistic.t(0d, oneSidedPStats),1E-10);
         Assert.assertEquals("one sample p value", 0.000521637019637,
                 testStatistic.tTest(0d, oneSidedP) / 2d, 10E-10);
         Assert.assertEquals("one sample p value", 0.000521637019637,
                 testStatistic.tTest(0d, oneSidedPStats) / 2d, 10E-5);
         Assert.assertTrue("one sample t-test reject", testStatistic.tTest(0d, oneSidedP, 0.01));
         Assert.assertTrue("one sample t-test reject", testStatistic.tTest(0d, oneSidedPStats, 0.01));
         Assert.assertFalse("one sample t-test accept", testStatistic.tTest(0d, oneSidedP, 0.0001));
         Assert.assertFalse("one sample t-test accept", testStatistic.tTest(0d, oneSidedPStats, 0.0001));
 
         try {
             testStatistic.tTest(0d, oneSidedP, 95);
             Assert.fail("alpha out of range, OutOfRangeException expected");
         } catch (OutOfRangeException ex) {
             // expected
         }
 
         try {
             testStatistic.tTest(0d, oneSidedPStats, 95);
             Assert.fail("alpha out of range, OutOfRangeException expected");
         } catch (OutOfRangeException ex) {
             // expected
         }
     }
 
     @Test
     public void testTwoSampleTHeterscedastic() {
         double[] sample1 = { 7d, -4d, 18d, 17d, -3d, -5d, 1d, 10d, 11d, -2d };
         double[] sample2 = { -1d, 12d, -1d, -3d, 3d, -5d, 5d, 2d, -11d, -1d, -3d };
         SummaryStatistics sampleStats1 = new SummaryStatistics();
         for (int i = 0; i < sample1.length; i++) {
             sampleStats1.addValue(sample1[i]);
         }
         SummaryStatistics sampleStats2 = new SummaryStatistics();
         for (int i = 0; i < sample2.length; i++) {
             sampleStats2.addValue(sample2[i]);
         }
 
         // Target comparison values computed using R version 1.8.1 (Linux version)
         Assert.assertEquals("two sample heteroscedastic t stat", 1.60371728768,
                 testStatistic.t(sample1, sample2), 1E-10);
         Assert.assertEquals("two sample heteroscedastic t stat", 1.60371728768,
                 testStatistic.t(sampleStats1, sampleStats2), 1E-10);
         Assert.assertEquals("two sample heteroscedastic p value", 0.128839369622,
                 testStatistic.tTest(sample1, sample2), 1E-10);
         Assert.assertEquals("two sample heteroscedastic p value", 0.128839369622,
                 testStatistic.tTest(sampleStats1, sampleStats2), 1E-10);
         Assert.assertTrue("two sample heteroscedastic t-test reject",
                 testStatistic.tTest(sample1, sample2, 0.2));
         Assert.assertTrue("two sample heteroscedastic t-test reject",
                 testStatistic.tTest(sampleStats1, sampleStats2, 0.2));
         Assert.assertFalse("two sample heteroscedastic t-test accept", testStatistic.tTest(sample1, sample2, 0.1));
         Assert.assertFalse("two sample heteroscedastic t-test accept", testStatistic.tTest(sampleStats1, sampleStats2, 0.1));
 
         try {
             testStatistic.tTest(sample1, sample2, .95);
             Assert.fail("alpha out of range, OutOfRangeException expected");
         } catch (OutOfRangeException ex) {
             // expected
         }
 
         try {
             testStatistic.tTest(sampleStats1, sampleStats2, .95);
             Assert.fail("alpha out of range, OutOfRangeException expected");
         } catch (OutOfRangeException ex) {
             // expected
         }
 
         try {
             testStatistic.tTest(sample1, tooShortObs, .01);
             Assert.fail("insufficient data, NumberIsTooSmallException expected");
         } catch (NumberIsTooSmallException ex) {
             // expected
         }
 
         try {
             testStatistic.tTest(sampleStats1, tooShortStats, .01);
             Assert.fail("insufficient data, NumberIsTooSmallException expected");
         } catch (NumberIsTooSmallException ex) {
             // expected
         }
 
         try {
             testStatistic.tTest(sample1, tooShortObs);
             Assert.fail("insufficient data, NumberIsTooSmallException expected");
         } catch (NumberIsTooSmallException ex) {
            // expected
         }
 
         try {
             testStatistic.tTest(sampleStats1, tooShortStats);
             Assert.fail("insufficient data, NumberIsTooSmallException expected");
         } catch (NumberIsTooSmallException ex) {
             // expected
         }
 
         try {
             testStatistic.t(sample1, tooShortObs);
             Assert.fail("insufficient data, NumberIsTooSmallException expected");
         } catch (NumberIsTooSmallException ex) {
             // expected
         }
 
         try {
             testStatistic.t(sampleStats1, tooShortStats);
             Assert.fail("insufficient data, NumberIsTooSmallException expected");
         } catch (NumberIsTooSmallException ex) {
            // expected
         }
     }
     @Test
     public void testTwoSampleTHomoscedastic() {
         double[] sample1 ={2, 4, 6, 8, 10, 97};
         double[] sample2 = {4, 6, 8, 10, 16};
         SummaryStatistics sampleStats1 = new SummaryStatistics();
         for (int i = 0; i < sample1.length; i++) {
             sampleStats1.addValue(sample1[i]);
         }
         SummaryStatistics sampleStats2 = new SummaryStatistics();
         for (int i = 0; i < sample2.length; i++) {
             sampleStats2.addValue(sample2[i]);
         }
 
         // Target comparison values computed using R version 1.8.1 (Linux version)
         Assert.assertEquals("two sample homoscedastic t stat", 0.73096310086,
               testStatistic.homoscedasticT(sample1, sample2), 10E-11);
         Assert.assertEquals("two sample homoscedastic p value", 0.4833963785,
                 testStatistic.homoscedasticTTest(sampleStats1, sampleStats2), 1E-10);
         Assert.assertTrue("two sample homoscedastic t-test reject",
                 testStatistic.homoscedasticTTest(sample1, sample2, 0.49));
         Assert.assertFalse("two sample homoscedastic t-test accept", testStatistic.homoscedasticTTest(sample1, sample2, 0.48));
     }
 
     @Test
     public void testSmallSamples() {
         double[] sample1 = {1d, 3d};
         double[] sample2 = {4d, 5d};
 
         // Target values computed using R, version 1.8.1 (linux version)
         Assert.assertEquals(-2.2360679775, testStatistic.t(sample1, sample2),
                 1E-10);
         Assert.assertEquals(0.198727388935, testStatistic.tTest(sample1, sample2),
                 1E-10);
     }
 
     @Test
     public void testPaired() {
         double[] sample1 = {1d, 3d, 5d, 7d};
         double[] sample2 = {0d, 6d, 11d, 2d};
         double[] sample3 = {5d, 7d, 8d, 10d};
 
         // Target values computed using R, version 1.8.1 (linux version)
         Assert.assertEquals(-0.3133, testStatistic.pairedT(sample1, sample2), 1E-4);
         Assert.assertEquals(0.774544295819, testStatistic.pairedTTest(sample1, sample2), 1E-10);
         Assert.assertEquals(0.001208, testStatistic.pairedTTest(sample1, sample3), 1E-6);
         Assert.assertFalse(testStatistic.pairedTTest(sample1, sample3, .001));
         Assert.assertTrue(testStatistic.pairedTTest(sample1, sample3, .002));
     }
 }