/*
    * 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
    *
    *      https://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.
   */
  
  /*
   * This is not the original file distributed by the Apache Software Foundation
   * It has been modified by the Hipparchus project
   */
  package org.hipparchus.stat.inference;
  
  
  import org.hipparchus.exception.MathIllegalArgumentException;
  import org.hipparchus.exception.NullArgumentException;
  import org.hipparchus.stat.descriptive.StreamingStatistics;
  import org.junit.jupiter.api.BeforeEach;
  import org.junit.jupiter.api.Test;
  
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.junit.jupiter.api.Assertions.assertFalse;
  import static org.junit.jupiter.api.Assertions.assertTrue;
  import static org.junit.jupiter.api.Assertions.fail;
  
  /**
   * Test cases for the TTestImpl class.
   *
   */
  class TTestTest {
  
      protected TTest testStatistic = new TTest();
  
      private double[] tooShortObs = { 1.0 };
      private double[] emptyObs = {};
      private StreamingStatistics emptyStats = new StreamingStatistics();
     StreamingStatistics tooShortStats = null;
  
      @BeforeEach
      void setUp() {
          tooShortStats = new StreamingStatistics();
          tooShortStats.addValue(0d);
      }
  
      @Test
      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;
          StreamingStatistics sampleStats = null;
          sampleStats = new StreamingStatistics();
          for (int i = 0; i < observed.length; i++) {
              sampleStats.addValue(observed[i]);
          }
  
          // Target comparison values computed using R version 1.8.1 (Linux version)
          assertEquals(-2.81976445346,
                  testStatistic.t(mu, observed), 10E-10, "t statistic");
          assertEquals(-2.81976445346,
                  testStatistic.t(mu, sampleStats), 10E-10, "t statistic");
          assertEquals(0.0136390585873,
                  testStatistic.tTest(mu, observed), 10E-10, "p value");
          assertEquals(0.0136390585873,
                  testStatistic.tTest(mu, sampleStats), 10E-10, "p value");
  
          try {
              testStatistic.t(mu, (double[]) null);
              fail("arguments too short, NullArgumentException expected");
          } catch (NullArgumentException ex) {
              // expected
          }
  
          try {
              testStatistic.t(mu, (StreamingStatistics) null);
              fail("arguments too short, NullArgumentException expected");
          } catch (NullArgumentException ex) {
              // expected
          }
  
          try {
              testStatistic.t(mu, emptyObs);
              fail("arguments too short, MathIllegalArgumentException expected");
          } catch (MathIllegalArgumentException ex) {
              // expected
          }
  
          try {
              testStatistic.t(mu, emptyStats);
              fail("arguments too short, MathIllegalArgumentException expected");
         } catch (MathIllegalArgumentException ex) {
             // expected
         }
 
         try {
             testStatistic.t(mu, tooShortObs);
             fail("insufficient data to compute t statistic, MathIllegalArgumentException expected");
         } catch (MathIllegalArgumentException ex) {
             // expected
         }
         try {
             testStatistic.tTest(mu, tooShortObs);
             fail("insufficient data to perform t test, MathIllegalArgumentException expected");
         } catch (MathIllegalArgumentException ex) {
            // expected
         }
 
         try {
             testStatistic.t(mu, tooShortStats);
             fail("insufficient data to compute t statistic, MathIllegalArgumentException expected");
         } catch (MathIllegalArgumentException ex) {
             // expected
         }
         try {
             testStatistic.tTest(mu, tooShortStats);
             fail("insufficient data to perform t test, MathIllegalArgumentException expected");
         } catch (MathIllegalArgumentException ex) {
             // expected
         }
     }
 
     @Test
     void testOneSampleTTest() {
         double[] oneSidedP =
             {2d, 0d, 6d, 6d, 3d, 3d, 2d, 3d, -6d, 6d, 6d, 6d, 3d, 0d, 1d, 1d, 0d, 2d, 3d, 3d };
         StreamingStatistics oneSidedPStats = new StreamingStatistics();
         for (int i = 0; i < oneSidedP.length; i++) {
             oneSidedPStats.addValue(oneSidedP[i]);
         }
         // Target comparison values computed using R version 1.8.1 (Linux version)
         assertEquals(3.86485535541,
                 testStatistic.t(0d, oneSidedP), 10E-10, "one sample t stat");
         assertEquals(3.86485535541,
                 testStatistic.t(0d, oneSidedPStats),1E-10,"one sample t stat");
         assertEquals(0.000521637019637,
                 testStatistic.tTest(0d, oneSidedP) / 2d, 10E-10, "one sample p value");
         assertEquals(0.000521637019637,
                 testStatistic.tTest(0d, oneSidedPStats) / 2d, 10E-5, "one sample p value");
         assertTrue(testStatistic.tTest(0d, oneSidedP, 0.01), "one sample t-test reject");
         assertTrue(testStatistic.tTest(0d, oneSidedPStats, 0.01), "one sample t-test reject");
         assertFalse(testStatistic.tTest(0d, oneSidedP, 0.0001), "one sample t-test accept");
         assertFalse(testStatistic.tTest(0d, oneSidedPStats, 0.0001), "one sample t-test accept");
 
         try {
             testStatistic.tTest(0d, oneSidedP, 95);
             fail("alpha out of range, MathIllegalArgumentException expected");
         } catch (MathIllegalArgumentException ex) {
             // expected
         }
 
         try {
             testStatistic.tTest(0d, oneSidedPStats, 95);
             fail("alpha out of range, MathIllegalArgumentException expected");
         } catch (MathIllegalArgumentException ex) {
             // expected
         }
 
     }
 
     @Test
     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 };
         StreamingStatistics sampleStats1 = new StreamingStatistics();
         for (int i = 0; i < sample1.length; i++) {
             sampleStats1.addValue(sample1[i]);
         }
         StreamingStatistics sampleStats2 = new StreamingStatistics();
         for (int i = 0; i < sample2.length; i++) {
             sampleStats2.addValue(sample2[i]);
         }
 
         // Target comparison values computed using R version 1.8.1 (Linux version)
         assertEquals(1.60371728768,
                 testStatistic.t(sample1, sample2), 1E-10, "two sample heteroscedastic t stat");
         assertEquals(1.60371728768,
                 testStatistic.t(sampleStats1, sampleStats2), 1E-10, "two sample heteroscedastic t stat");
         assertEquals(0.128839369622,
                 testStatistic.tTest(sample1, sample2), 1E-10, "two sample heteroscedastic p value");
         assertEquals(0.128839369622,
                 testStatistic.tTest(sampleStats1, sampleStats2), 1E-10, "two sample heteroscedastic p value");
         assertTrue(testStatistic.tTest(sample1, sample2, 0.2),
                 "two sample heteroscedastic t-test reject");
         assertTrue(testStatistic.tTest(sampleStats1, sampleStats2, 0.2),
                 "two sample heteroscedastic t-test reject");
         assertFalse(testStatistic.tTest(sample1, sample2, 0.1), "two sample heteroscedastic t-test accept");
         assertFalse(testStatistic.tTest(sampleStats1, sampleStats2, 0.1), "two sample heteroscedastic t-test accept");
 
         try {
             testStatistic.tTest(sample1, sample2, .95);
             fail("alpha out of range, MathIllegalArgumentException expected");
         } catch (MathIllegalArgumentException ex) {
             // expected
         }
 
         try {
             testStatistic.tTest(sampleStats1, sampleStats2, .95);
             fail("alpha out of range, MathIllegalArgumentException expected");
         } catch (MathIllegalArgumentException ex) {
             // expected
         }
 
         try {
             testStatistic.tTest(sample1, tooShortObs, .01);
             fail("insufficient data, MathIllegalArgumentException expected");
         } catch (MathIllegalArgumentException ex) {
             // expected
         }
 
         try {
             testStatistic.tTest(sampleStats1, tooShortStats, .01);
             fail("insufficient data, MathIllegalArgumentException expected");
         } catch (MathIllegalArgumentException ex) {
             // expected
         }
 
         try {
             testStatistic.tTest(sample1, tooShortObs);
             fail("insufficient data, MathIllegalArgumentException expected");
         } catch (MathIllegalArgumentException ex) {
            // expected
         }
 
         try {
             testStatistic.tTest(sampleStats1, tooShortStats);
             fail("insufficient data, MathIllegalArgumentException expected");
         } catch (MathIllegalArgumentException ex) {
             // expected
         }
 
         try {
             testStatistic.t(sample1, tooShortObs);
             fail("insufficient data, MathIllegalArgumentException expected");
         } catch (MathIllegalArgumentException ex) {
             // expected
         }
 
         try {
             testStatistic.t(sampleStats1, tooShortStats);
             fail("insufficient data, MathIllegalArgumentException expected");
         } catch (MathIllegalArgumentException ex) {
            // expected
         }
     }
 
     @Test
     void testTwoSampleTHomoscedastic() {
         double[] sample1 ={2, 4, 6, 8, 10, 97};
         double[] sample2 = {4, 6, 8, 10, 16};
         StreamingStatistics sampleStats1 = new StreamingStatistics();
         for (int i = 0; i < sample1.length; i++) {
             sampleStats1.addValue(sample1[i]);
         }
         StreamingStatistics sampleStats2 = new StreamingStatistics();
         for (int i = 0; i < sample2.length; i++) {
             sampleStats2.addValue(sample2[i]);
         }
 
         // Target comparison values computed using R version 1.8.1 (Linux version)
         assertEquals(0.73096310086,
               testStatistic.homoscedasticT(sample1, sample2), 10E-11, "two sample homoscedastic t stat");
         assertEquals(0.4833963785,
                 testStatistic.homoscedasticTTest(sampleStats1, sampleStats2), 1E-10, "two sample homoscedastic p value");
         assertTrue(testStatistic.homoscedasticTTest(sample1, sample2, 0.49),
                 "two sample homoscedastic t-test reject");
         assertFalse(testStatistic.homoscedasticTTest(sample1, sample2, 0.48), "two sample homoscedastic t-test accept");
     }
 
     @Test
     void testSmallSamples() {
         double[] sample1 = {1d, 3d};
         double[] sample2 = {4d, 5d};
 
         // Target values computed using R, version 1.8.1 (linux version)
         assertEquals(-2.2360679775, testStatistic.t(sample1, sample2),
                 1E-10);
         assertEquals(0.198727388935, testStatistic.tTest(sample1, sample2),
                 1E-10);
     }
 
     @Test
     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)
         assertEquals(-0.3133, testStatistic.pairedT(sample1, sample2), 1E-4);
         assertEquals(0.774544295819, testStatistic.pairedTTest(sample1, sample2), 1E-10);
         assertEquals(0.001208, testStatistic.pairedTTest(sample1, sample3), 1E-6);
         assertFalse(testStatistic.pairedTTest(sample1, sample3, .001));
         assertTrue(testStatistic.pairedTTest(sample1, sample3, .002));
     }
 }