/*
 * 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.math.stat.inference;

import junit.framework.Test;
import junit.framework.TestCase;
import junit.framework.TestSuite;

import org.apache.commons.math.stat.descriptive.SummaryStatistics;

/**
 * Test cases for the TTestImpl class.
 *
 * @version $Revision$ $Date$
 */

public class TTestTest extends TestCase {

	protected TTest testStatistic = new TTestImpl();

	private double[] tooShortObs = { 1.0 };
	private double[] emptyObs = {};
	private SummaryStatistics emptyStats = new SummaryStatistics();
	SummaryStatistics tooShortStats = null;

	public TTestTest(String name) {
		super(name);
	}

	@Override
	public void setUp() {
		tooShortStats = new SummaryStatistics();
		tooShortStats.addValue(0d);
	}

	public static Test suite() {
		TestSuite suite = new TestSuite(TTestTest.class);
		suite.setName("TestStatistic Tests");
		return suite;
	}

	public void testOneSampleT() throws Exception {
		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)
		assertEquals("t statistic", -2.81976445346, testStatistic.t(mu, observed), 10E-10);
		assertEquals("t statistic", -2.81976445346, testStatistic.t(mu, sampleStats), 10E-10);
		assertEquals("p value", 0.0136390585873, testStatistic.tTest(mu, observed), 10E-10);
		assertEquals("p value", 0.0136390585873, testStatistic.tTest(mu, sampleStats), 10E-10);

		try {
			testStatistic.t(mu, (double[]) null);
			fail("arguments too short, IllegalArgumentException expected");
		} catch (IllegalArgumentException ex) {
			// expected
		}

		try {
			testStatistic.t(mu, (SummaryStatistics) null);
			fail("arguments too short, IllegalArgumentException expected");
		} catch (IllegalArgumentException ex) {
			// expected
		}

		try {
			testStatistic.t(mu, emptyObs);
			fail("arguments too short, IllegalArgumentException expected");
		} catch (IllegalArgumentException ex) {
			// expected
		}

		try {
			testStatistic.t(mu, emptyStats);
			fail("arguments too short, IllegalArgumentException expected");
		} catch (IllegalArgumentException ex) {
			// expected
		}

		try {
			testStatistic.t(mu, tooShortObs);
			fail("insufficient data to compute t statistic, IllegalArgumentException expected");
		} catch (IllegalArgumentException ex) {
			// expected
		}
		try {
			testStatistic.tTest(mu, tooShortObs);
			fail("insufficient data to perform t test, IllegalArgumentException expected");
		} catch (IllegalArgumentException ex) {
			// expected
		}

		try {
			testStatistic.t(mu, tooShortStats);
			fail("insufficient data to compute t statistic, IllegalArgumentException expected");
		} catch (IllegalArgumentException ex) {
			// expected
		}
		try {
			testStatistic.tTest(mu, tooShortStats);
			fail("insufficient data to perform t test, IllegalArgumentException expected");
		} catch (IllegalArgumentException ex) {
			// expected
		}
	}

	public void testOneSampleTTest() throws Exception {
		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)
		assertEquals("one sample t stat", 3.86485535541, testStatistic.t(0d, oneSidedP), 10E-10);
		assertEquals("one sample t stat", 3.86485535541, testStatistic.t(0d, oneSidedPStats), 1E-10);
		assertEquals("one sample p value", 0.000521637019637, testStatistic.tTest(0d, oneSidedP) / 2d, 10E-10);
		assertEquals("one sample p value", 0.000521637019637, testStatistic.tTest(0d, oneSidedPStats) / 2d, 10E-5);
		assertTrue("one sample t-test reject", testStatistic.tTest(0d, oneSidedP, 0.01));
		assertTrue("one sample t-test reject", testStatistic.tTest(0d, oneSidedPStats, 0.01));
		assertTrue("one sample t-test accept", !testStatistic.tTest(0d, oneSidedP, 0.0001));
		assertTrue("one sample t-test accept", !testStatistic.tTest(0d, oneSidedPStats, 0.0001));

		try {
			testStatistic.tTest(0d, oneSidedP, 95);
			fail("alpha out of range, IllegalArgumentException expected");
		} catch (IllegalArgumentException ex) {
			// expected
		}

		try {
			testStatistic.tTest(0d, oneSidedPStats, 95);
			fail("alpha out of range, IllegalArgumentException expected");
		} catch (IllegalArgumentException ex) {
			// expected
		}

	}

	public void testTwoSampleTHeterscedastic() throws Exception {
		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)
		assertEquals("two sample heteroscedastic t stat", 1.60371728768, testStatistic.t(sample1, sample2), 1E-10);
		assertEquals("two sample heteroscedastic t stat", 1.60371728768, testStatistic.t(sampleStats1, sampleStats2),
				1E-10);
		assertEquals("two sample heteroscedastic p value", 0.128839369622, testStatistic.tTest(sample1, sample2),
				1E-10);
		assertEquals("two sample heteroscedastic p value", 0.128839369622,
				testStatistic.tTest(sampleStats1, sampleStats2), 1E-10);
		assertTrue("two sample heteroscedastic t-test reject", testStatistic.tTest(sample1, sample2, 0.2));
		assertTrue("two sample heteroscedastic t-test reject", testStatistic.tTest(sampleStats1, sampleStats2, 0.2));
		assertTrue("two sample heteroscedastic t-test accept", !testStatistic.tTest(sample1, sample2, 0.1));
		assertTrue("two sample heteroscedastic t-test accept", !testStatistic.tTest(sampleStats1, sampleStats2, 0.1));

		try {
			testStatistic.tTest(sample1, sample2, .95);
			fail("alpha out of range, IllegalArgumentException expected");
		} catch (IllegalArgumentException ex) {
			// expected
		}

		try {
			testStatistic.tTest(sampleStats1, sampleStats2, .95);
			fail("alpha out of range, IllegalArgumentException expected");
		} catch (IllegalArgumentException ex) {
			// expected
		}

		try {
			testStatistic.tTest(sample1, tooShortObs, .01);
			fail("insufficient data, IllegalArgumentException expected");
		} catch (IllegalArgumentException ex) {
			// expected
		}

		try {
			testStatistic.tTest(sampleStats1, tooShortStats, .01);
			fail("insufficient data, IllegalArgumentException expected");
		} catch (IllegalArgumentException ex) {
			// expected
		}

		try {
			testStatistic.tTest(sample1, tooShortObs);
			fail("insufficient data, IllegalArgumentException expected");
		} catch (IllegalArgumentException ex) {
			// expected
		}

		try {
			testStatistic.tTest(sampleStats1, tooShortStats);
			fail("insufficient data, IllegalArgumentException expected");
		} catch (IllegalArgumentException ex) {
			// expected
		}

		try {
			testStatistic.t(sample1, tooShortObs);
			fail("insufficient data, IllegalArgumentException expected");
		} catch (IllegalArgumentException ex) {
			// expected
		}

		try {
			testStatistic.t(sampleStats1, tooShortStats);
			fail("insufficient data, IllegalArgumentException expected");
		} catch (IllegalArgumentException ex) {
			// expected
		}
	}

	public void testTwoSampleTHomoscedastic() throws Exception {
		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)
		assertEquals("two sample homoscedastic t stat", 0.73096310086, testStatistic.homoscedasticT(sample1, sample2),
				10E-11);
		assertEquals("two sample homoscedastic p value", 0.4833963785,
				testStatistic.homoscedasticTTest(sampleStats1, sampleStats2), 1E-10);
		assertTrue("two sample homoscedastic t-test reject", testStatistic.homoscedasticTTest(sample1, sample2, 0.49));
		assertTrue("two sample homoscedastic t-test accept", !testStatistic.homoscedasticTTest(sample1, sample2, 0.48));
	}

	public void testSmallSamples() throws Exception {
		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);
	}

	public void testPaired() throws Exception {
		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));
	}
}
