TestCorrel.java

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   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
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   distributed under the License is distributed on an "AS IS" BASIS,
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package org.apache.poi.ss.formula.functions;

import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFFormulaEvaluator;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.FormulaError;
import org.junit.jupiter.api.Test;

import java.io.IOException;

import static org.apache.poi.ss.util.Utils.addRow;
import static org.apache.poi.ss.util.Utils.assertDouble;
import static org.apache.poi.ss.util.Utils.assertError;

/**
 * Tests for {@link Correl}
 */
final class TestCorrel {

    //https://support.microsoft.com/en-us/office/correl-function-995dcef7-0c0a-4bed-a3fb-239d7b68ca92
    @Test
    void testMicrosoftExample1() throws IOException {
        try (HSSFWorkbook wb = initWorkbook1()) {
            HSSFSheet sheet = wb.getSheetAt(0);
            HSSFRow row = sheet.getRow(0);
            HSSFCell cell = row.createCell(100);
            HSSFFormulaEvaluator fe = new HSSFFormulaEvaluator(wb);
            assertDouble(fe, cell, "CORREL(A2:A6,B2:B6)", 0.997054486, 0.0000000005);
        }
    }

    //https://support.microsoft.com/en-us/office/pearson-function-0c3e30fc-e5af-49c4-808a-3ef66e034c18
    @Test
    void testPearsonExample1() throws IOException {
        try (HSSFWorkbook wb = initWorkbook2()) {
            HSSFSheet sheet = wb.getSheetAt(0);
            HSSFRow row = sheet.getRow(0);
            HSSFCell cell = row.createCell(100);
            HSSFFormulaEvaluator fe = new HSSFFormulaEvaluator(wb);
            assertDouble(fe, cell, "CORREL(A2:A6,B2:B6)", 0.699379, 0.0000005);
            assertDouble(fe, cell, "PEARSON(A2:A6,B2:B6)", 0.699379, 0.0000005);
        }
    }

    @Test
    void testBlankValue() throws IOException {
        try (HSSFWorkbook wb = initWorkbook1(null)) {
            HSSFSheet sheet = wb.getSheetAt(0);
            HSSFRow row = sheet.getRow(0);
            HSSFCell cell = row.createCell(100);
            HSSFFormulaEvaluator fe = new HSSFFormulaEvaluator(wb);
            assertDouble(fe, cell, "CORREL(A2:A6,B2:B6)", 0.9984884738, 0.0000000005);
        }
    }

    @Test
    void testStringValue() throws IOException {
        try (HSSFWorkbook wb = initWorkbook1("string")) {
            HSSFSheet sheet = wb.getSheetAt(0);
            HSSFRow row = sheet.getRow(0);
            HSSFCell cell = row.createCell(100);
            HSSFFormulaEvaluator fe = new HSSFFormulaEvaluator(wb);
            assertDouble(fe, cell, "CORREL(A2:A6,B2:B6)", 0.9984884738, 0.0000000005);
        }
    }

    @Test
    void testMismatch() throws IOException {
        try (HSSFWorkbook wb = initWorkbook1()) {
            HSSFSheet sheet = wb.getSheetAt(0);
            HSSFRow row = sheet.getRow(0);
            HSSFCell cell = row.createCell(100);
            HSSFFormulaEvaluator fe = new HSSFFormulaEvaluator(wb);
            assertError(fe, cell, "CORREL(A2:A6,B2:B5)", FormulaError.NA);
            assertError(fe, cell, "CORREL(A2:B6,B2:B6)", FormulaError.NA);
        }
    }

    private HSSFWorkbook initWorkbook1() {
        return initWorkbook1(Double.valueOf(15));
    }

    private HSSFWorkbook initWorkbook1(Object row4Data2) {
        HSSFWorkbook wb = new HSSFWorkbook();
        HSSFSheet sheet = wb.createSheet();
        addRow(sheet, 0, "Data1", "Data2");
        addRow(sheet, 1, 3, 9);
        addRow(sheet, 2, 2, 7);
        addRow(sheet, 3, 4, 12);
        addRow(sheet, 4, 5, row4Data2);
        addRow(sheet, 5, 6, 17);
        return wb;
    }

    private HSSFWorkbook initWorkbook2() {
        HSSFWorkbook wb = new HSSFWorkbook();
        HSSFSheet sheet = wb.createSheet();
        addRow(sheet, 0, "Independent values", "Dependent values");
        addRow(sheet, 1, 9, 10);
        addRow(sheet, 2, 7, 6);
        addRow(sheet, 3, 5, 1);
        addRow(sheet, 4, 3, 5);
        addRow(sheet, 5, 1, 3);
        return wb;
    }
}