/*
 * 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;

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

public class ChiSquareTestTest extends TestCase {

	protected UnknownDistributionChiSquareTest testStatistic = new ChiSquareTestImpl();

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

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

	public void testChiSquare() throws Exception {

		// Target values computed using R version 1.8.1
		// Some assembly required ;-)
		// Use sum((obs - exp)^2/exp) for the chi-square statistic and
		// 1 - pchisq(sum((obs - exp)^2/exp), length(obs) - 1) for the p-value

		long[] observed = { 10, 9, 11 };
		double[] expected = { 10, 10, 10 };
		assertEquals("chi-square statistic", 0.2, testStatistic.chiSquare(expected, observed), 10E-12);
		assertEquals("chi-square p-value", 0.904837418036, testStatistic.chiSquareTest(expected, observed), 1E-10);

		long[] observed1 = { 500, 623, 72, 70, 31 };
		double[] expected1 = { 485, 541, 82, 61, 37 };
		assertEquals("chi-square test statistic", 9.023307936427388, testStatistic.chiSquare(expected1, observed1),
				1E-10);
		assertEquals("chi-square p-value", 0.06051952647453607, testStatistic.chiSquareTest(expected1, observed1),
				1E-9);
		assertTrue("chi-square test reject", testStatistic.chiSquareTest(expected1, observed1, 0.08));
		assertTrue("chi-square test accept", !testStatistic.chiSquareTest(expected1, observed1, 0.05));

		try {
			testStatistic.chiSquareTest(expected1, observed1, 95);
			fail("alpha out of range, IllegalArgumentException expected");
		} catch (IllegalArgumentException ex) {
			// expected
		}

		long[] tooShortObs = { 0 };
		double[] tooShortEx = { 1 };
		try {
			testStatistic.chiSquare(tooShortEx, tooShortObs);
			fail("arguments too short, IllegalArgumentException expected");
		} catch (IllegalArgumentException ex) {
			// expected
		}

		// unmatched arrays
		long[] unMatchedObs = { 0, 1, 2, 3 };
		double[] unMatchedEx = { 1, 1, 2 };
		try {
			testStatistic.chiSquare(unMatchedEx, unMatchedObs);
			fail("arrays have different lengths, IllegalArgumentException expected");
		} catch (IllegalArgumentException ex) {
			// expected
		}

		// 0 expected count
		expected[0] = 0;
		try {
			testStatistic.chiSquareTest(expected, observed, .01);
			fail("bad expected count, IllegalArgumentException expected");
		} catch (IllegalArgumentException ex) {
			// expected
		}

		// negative observed count
		expected[0] = 1;
		observed[0] = -1;
		try {
			testStatistic.chiSquareTest(expected, observed, .01);
			fail("bad expected count, IllegalArgumentException expected");
		} catch (IllegalArgumentException ex) {
			// expected
		}

	}

	public void testChiSquareIndependence() throws Exception {

		// Target values computed using R version 1.8.1

		long[][] counts = { { 40, 22, 43 }, { 91, 21, 28 }, { 60, 10, 22 } };
		assertEquals("chi-square test statistic", 22.709027688, testStatistic.chiSquare(counts), 1E-9);
		assertEquals("chi-square p-value", 0.000144751460134, testStatistic.chiSquareTest(counts), 1E-9);
		assertTrue("chi-square test reject", testStatistic.chiSquareTest(counts, 0.0002));
		assertTrue("chi-square test accept", !testStatistic.chiSquareTest(counts, 0.0001));

		long[][] counts2 = { { 10, 15 }, { 30, 40 }, { 60, 90 } };
		assertEquals("chi-square test statistic", 0.168965517241, testStatistic.chiSquare(counts2), 1E-9);
		assertEquals("chi-square p-value", 0.918987499852, testStatistic.chiSquareTest(counts2), 1E-9);
		assertTrue("chi-square test accept", !testStatistic.chiSquareTest(counts2, 0.1));

		// ragged input array
		long[][] counts3 = { { 40, 22, 43 }, { 91, 21, 28 }, { 60, 10 } };
		try {
			testStatistic.chiSquare(counts3);
			fail("Expecting IllegalArgumentException");
		} catch (IllegalArgumentException ex) {
			// expected
		}

		// insufficient data
		long[][] counts4 = { { 40, 22, 43 } };
		try {
			testStatistic.chiSquare(counts4);
			fail("Expecting IllegalArgumentException");
		} catch (IllegalArgumentException ex) {
			// expected
		}
		long[][] counts5 = { { 40 }, { 40 }, { 30 }, { 10 } };
		try {
			testStatistic.chiSquare(counts5);
			fail("Expecting IllegalArgumentException");
		} catch (IllegalArgumentException ex) {
			// expected
		}

		// negative counts
		long[][] counts6 = { { 10, -2 }, { 30, 40 }, { 60, 90 } };
		try {
			testStatistic.chiSquare(counts6);
			fail("Expecting IllegalArgumentException");
		} catch (IllegalArgumentException ex) {
			// expected
		}

		// bad alpha
		try {
			testStatistic.chiSquareTest(counts, 0);
			fail("Expecting IllegalArgumentException");
		} catch (IllegalArgumentException ex) {
			// expected
		}
	}

	public void testChiSquareLargeTestStatistic() throws Exception {
		double[] exp = new double[] { 3389119.5, 649136.6, 285745.4, 25357364.76, 11291189.78, 543628.0, 232921.0,
				437665.75 };

		long[] obs = new long[] { 2372383, 584222, 257170, 17750155, 7903832, 489265, 209628, 393899 };
		org.apache.commons.math.stat.inference.ChiSquareTestImpl csti = new org.apache.commons.math.stat.inference.ChiSquareTestImpl();
		double cst = csti.chiSquareTest(exp, obs);
		assertEquals("chi-square p-value", 0.0, cst, 1E-3);
		assertEquals("chi-square test statistic", 114875.90421929007, testStatistic.chiSquare(exp, obs), 1E-9);
	}

	/** Contingency table containing zeros - PR # 32531 */
	public void testChiSquareZeroCount() throws Exception {
		// Target values computed using R version 1.8.1
		long[][] counts = { { 40, 0, 4 }, { 91, 1, 2 }, { 60, 2, 0 } };
		assertEquals("chi-square test statistic", 9.67444662263, testStatistic.chiSquare(counts), 1E-9);
		assertEquals("chi-square p-value", 0.0462835770603, testStatistic.chiSquareTest(counts), 1E-9);
	}

	/** Target values verified using DATAPLOT version 2006.3 */
	public void testChiSquareDataSetsComparisonEqualCounts() throws Exception {
		long[] observed1 = { 10, 12, 12, 10 };
		long[] observed2 = { 5, 15, 14, 10 };
		assertEquals("chi-square p value", 0.541096,
				testStatistic.chiSquareTestDataSetsComparison(observed1, observed2), 1E-6);
		assertEquals("chi-square test statistic", 2.153846,
				testStatistic.chiSquareDataSetsComparison(observed1, observed2), 1E-6);
		assertFalse("chi-square test result", testStatistic.chiSquareTestDataSetsComparison(observed1, observed2, 0.4));
	}

	/** Target values verified using DATAPLOT version 2006.3 */
	public void testChiSquareDataSetsComparisonUnEqualCounts() throws Exception {
		long[] observed1 = { 10, 12, 12, 10, 15 };
		long[] observed2 = { 15, 10, 10, 15, 5 };
		assertEquals("chi-square p value", 0.124115,
				testStatistic.chiSquareTestDataSetsComparison(observed1, observed2), 1E-6);
		assertEquals("chi-square test statistic", 7.232189,
				testStatistic.chiSquareDataSetsComparison(observed1, observed2), 1E-6);
		assertTrue("chi-square test result", testStatistic.chiSquareTestDataSetsComparison(observed1, observed2, 0.13));
		assertFalse("chi-square test result",
				testStatistic.chiSquareTestDataSetsComparison(observed1, observed2, 0.12));
	}

	public void testChiSquareDataSetsComparisonBadCounts() throws Exception {
		long[] observed1 = { 10, -1, 12, 10, 15 };
		long[] observed2 = { 15, 10, 10, 15, 5 };
		try {
			testStatistic.chiSquareTestDataSetsComparison(observed1, observed2);
			fail("Expecting IllegalArgumentException - negative count");
		} catch (IllegalArgumentException ex) {
			// expected
		}
		long[] observed3 = { 10, 0, 12, 10, 15 };
		long[] observed4 = { 15, 0, 10, 15, 5 };
		try {
			testStatistic.chiSquareTestDataSetsComparison(observed3, observed4);
			fail("Expecting IllegalArgumentException - double 0's");
		} catch (IllegalArgumentException ex) {
			// expected
		}
		long[] observed5 = { 10, 10, 12, 10, 15 };
		long[] observed6 = { 0, 0, 0, 0, 0 };
		try {
			testStatistic.chiSquareTestDataSetsComparison(observed5, observed6);
			fail("Expecting IllegalArgumentException - vanishing counts");
		} catch (IllegalArgumentException ex) {
			// expected
		}
	}
}
