[bug-66105] support CORREL function

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1901670 13f79535-47bb-0310-9956-ffa450edef68

6 files changed, 229 insertions, 33 deletions

diff --git a/poi/src/main/java/org/apache/poi/ss/formula/eval/FunctionEval.java b/poi/src/main/java/org/apache/poi/ss/formula/eval/FunctionEval.java
index eb322007fd..e08989ef27 100644
--- a/poi/src/main/java/org/apache/poi/ss/formula/eval/FunctionEval.java
+++ b/poi/src/main/java/org/apache/poi/ss/formula/eval/FunctionEval.java
@@ -287,7 +287,7 @@ public final class FunctionEval {
         retval[304] = new Sumx2my2();
         retval[305] = new Sumx2py2();
         // 306: CHITEST
-        // 307: CORREL
+        retval[307] = Correl.instance;
         // 308: COVAR
         // 309: FORECAST
         // 310: FTEST
diff --git a/poi/src/main/java/org/apache/poi/ss/formula/functions/Correl.java b/poi/src/main/java/org/apache/poi/ss/formula/functions/Correl.java
new file mode 100644
index 0000000000..34c871bdb3
--- /dev/null
+++ b/poi/src/main/java/org/apache/poi/ss/formula/functions/Correl.java
@@ -0,0 +1,135 @@
+/* ====================================================================
+   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.poi.ss.formula.functions;
+
+import org.apache.commons.math3.stat.correlation.PearsonsCorrelation;
+import org.apache.poi.ss.formula.ThreeDEval;
+import org.apache.poi.ss.formula.TwoDEval;
+import org.apache.poi.ss.formula.eval.BlankEval;
+import org.apache.poi.ss.formula.eval.ErrorEval;
+import org.apache.poi.ss.formula.eval.EvaluationException;
+import org.apache.poi.ss.formula.eval.NumberEval;
+import org.apache.poi.ss.formula.eval.NumericValueEval;
+import org.apache.poi.ss.formula.eval.OperandResolver;
+import org.apache.poi.ss.formula.eval.RefEval;
+import org.apache.poi.ss.formula.eval.StringValueEval;
+import org.apache.poi.ss.formula.eval.ValueEval;
+
+/**
+ * Implementation for Excel CORREL() function.
+ * <p>
+ *   <b>Syntax</b>:<br> <b>CORREL </b>(<b>array1</b>, <b>array2</b>)<br>
+ * </p>
+ * <p>
+ *   The CORREL function returns the correlation coefficient of two cell ranges.
+ *   Use the correlation coefficient to determine the relationship between two properties.
+ *   For example, you can examine the relationship between a location's average temperature and the use of air conditioners.
+ * </p>
+ * <p>
+ *   See https://support.microsoft.com/en-us/office/correl-function-995dcef7-0c0a-4bed-a3fb-239d7b68ca92
+ * </p>
+ */
+public class Correl extends Fixed2ArgFunction {
+
+    public static final Correl instance = new Correl();
+
+    @Override
+    public ValueEval evaluate(int srcRowIndex, int srcColumnIndex, ValueEval arg0, ValueEval arg1) {
+        try {
+            final PearsonsCorrelation pc = new PearsonsCorrelation();
+            final double correl = pc.correlation(
+                    getNumberArray(arg0), getNumberArray(arg1));
+            return new NumberEval(correl);
+        } catch (EvaluationException e) {
+            return e.getErrorEval();
+        }
+    }
+
+    private double[] getNumberArray(ValueEval operand) throws EvaluationException {
+        DoubleList retval = new DoubleList();
+        collectValues(operand, retval);
+        return retval.toArray();
+    }
+
+    private void collectValues(ValueEval operand, DoubleList temp) throws EvaluationException {
+        if (operand instanceof ThreeDEval) {
+            ThreeDEval ae = (ThreeDEval) operand;
+            for (int sIx = ae.getFirstSheetIndex(); sIx <= ae.getLastSheetIndex(); sIx++) {
+                int width = ae.getWidth();
+                int height = ae.getHeight();
+                for (int rrIx = 0; rrIx < height; rrIx++) {
+                    for (int rcIx = 0; rcIx < width; rcIx++) {
+                        ValueEval ve = ae.getValue(sIx, rrIx, rcIx);
+                        collectValue(ve, temp);
+                    }
+                }
+            }
+            return;
+        }
+        if (operand instanceof TwoDEval) {
+            TwoDEval ae = (TwoDEval) operand;
+            int width = ae.getWidth();
+            int height = ae.getHeight();
+            for (int rrIx = 0; rrIx < height; rrIx++) {
+                for (int rcIx = 0; rcIx < width; rcIx++) {
+                    ValueEval ve = ae.getValue(rrIx, rcIx);
+                    collectValue(ve, temp);
+                }
+            }
+            return;
+        }
+        if (operand instanceof RefEval) {
+            RefEval re = (RefEval) operand;
+            for (int sIx = re.getFirstSheetIndex(); sIx <= re.getLastSheetIndex(); sIx++) {
+                collectValue(re.getInnerValueEval(sIx), temp);
+            }
+            return;
+        }
+        collectValue(operand, temp);
+    }
+
+    private void collectValue(ValueEval ve, DoubleList temp) throws EvaluationException {
+        if (ve == null) {
+            throw new IllegalArgumentException("ve must not be null");
+        }
+        if (ve instanceof NumericValueEval) {
+            NumericValueEval ne = (NumericValueEval) ve;
+            temp.add(ne.getNumberValue());
+            return;
+        }
+        if (ve instanceof StringValueEval) {
+            String s = ((StringValueEval) ve).getStringValue().trim();
+            Double d = OperandResolver.parseDouble(s);
+            if (d == null) {
+                throw new EvaluationException(ErrorEval.VALUE_INVALID);
+            } else {
+                temp.add(d.doubleValue());
+            }
+            return;
+        }
+        if (ve instanceof ErrorEval) {
+            throw new EvaluationException((ErrorEval) ve);
+        }
+        if (ve == BlankEval.instance) {
+            temp.add(0.0);
+            return;
+        }
+        throw new RuntimeException("Invalid ValueEval type passed for conversion: ("
+                + ve.getClass() + ")");
+    }
+
+}
diff --git a/poi/src/main/java/org/apache/poi/ss/formula/functions/DoubleList.java b/poi/src/main/java/org/apache/poi/ss/formula/functions/DoubleList.java
new file mode 100644
index 0000000000..e257bab2f6
--- /dev/null
+++ b/poi/src/main/java/org/apache/poi/ss/formula/functions/DoubleList.java
@@ -0,0 +1,32 @@
+package org.apache.poi.ss.formula.functions;
+
+import java.util.Arrays;
+
+final class DoubleList {
+    static final double[] EMPTY_DOUBLE_ARRAY = {};
+
+    private double[] _array;
+    private int _count;
+
+    public DoubleList() {
+        _array = new double[8];
+        _count = 0;
+    }
+
+    public double[] toArray() {
+        return _count < 1 ? EMPTY_DOUBLE_ARRAY : Arrays.copyOf(_array, _count);
+    }
+
+    private void ensureCapacity(int reqSize) {
+        if (reqSize > _array.length) {
+            int newSize = reqSize * 3 / 2; // grow with 50% extra
+            _array = Arrays.copyOf(_array, newSize);
+        }
+    }
+
+    public void add(double value) {
+        ensureCapacity(_count + 1);
+        _array[_count] = value;
+        _count++;
+    }
+}
diff --git a/poi/src/main/java/org/apache/poi/ss/formula/functions/MultiOperandNumericFunction.java b/poi/src/main/java/org/apache/poi/ss/formula/functions/MultiOperandNumericFunction.java
index 86a2741fff..adbddd8ba4 100644
--- a/poi/src/main/java/org/apache/poi/ss/formula/functions/MultiOperandNumericFunction.java
+++ b/poi/src/main/java/org/apache/poi/ss/formula/functions/MultiOperandNumericFunction.java
@@ -17,8 +17,6 @@
 
 package org.apache.poi.ss.formula.functions;
 
-import java.util.Arrays;
-
 import org.apache.poi.ss.SpreadsheetVersion;
 import org.apache.poi.ss.formula.ThreeDEval;
 import org.apache.poi.ss.formula.TwoDEval;
@@ -57,35 +55,6 @@ public abstract class MultiOperandNumericFunction implements Function {
         blankConsumer = ConsumerFactory.createForBlank(isBlankCounted ? Policy.COERCE : Policy.SKIP);
     }
 
-    static final double[] EMPTY_DOUBLE_ARRAY = {};
-
-    private static class DoubleList {
-        private double[] _array;
-        private int _count;
-
-        public DoubleList() {
-            _array = new double[8];
-            _count = 0;
-        }
-
-        public double[] toArray() {
-            return _count < 1 ? EMPTY_DOUBLE_ARRAY : Arrays.copyOf(_array, _count);
-        }
-
-        private void ensureCapacity(int reqSize) {
-            if (reqSize > _array.length) {
-                int newSize = reqSize * 3 / 2; // grow with 50% extra
-                _array = Arrays.copyOf(_array, newSize);
-            }
-        }
-
-        public void add(double value) {
-            ensureCapacity(_count + 1);
-            _array[_count] = value;
-            _count++;
-        }
-    }
-
     private static final int DEFAULT_MAX_NUM_OPERANDS = SpreadsheetVersion.EXCEL2007.getMaxFunctionArgs();
 
     public void setMissingArgPolicy(Policy policy) {
diff --git a/poi/src/main/java/org/apache/poi/ss/formula/functions/Sqrtpi.java b/poi/src/main/java/org/apache/poi/ss/formula/functions/Sqrtpi.java
index dbd02b3c3b..9c51cc967a 100644
--- a/poi/src/main/java/org/apache/poi/ss/formula/functions/Sqrtpi.java
+++ b/poi/src/main/java/org/apache/poi/ss/formula/functions/Sqrtpi.java
@@ -27,7 +27,7 @@ import org.apache.poi.ss.util.NumberToTextConverter;
 /**
  * Implementation for Excel SQRTPI() function.
  * <p>
- *   <b>Syntax</b>:<br> <b>SQRT  </b>(<b>number</b>)<br>
+ *   <b>Syntax</b>:<br> <b>SQRTPI </b>(<b>number</b>)<br>
  * </p>
  * <p>
  *   Returns the square root of (number * pi).
diff --git a/poi/src/test/java/org/apache/poi/ss/formula/functions/TestCorrel.java b/poi/src/test/java/org/apache/poi/ss/formula/functions/TestCorrel.java
new file mode 100644
index 0000000000..dc18477a39
--- /dev/null
+++ b/poi/src/test/java/org/apache/poi/ss/formula/functions/TestCorrel.java
@@ -0,0 +1,60 @@
+/* ====================================================================
+   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.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.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;
+
+/**
+ * Tests for {@link Correl}
+ */
+final class TestCorrel {
+
+    //https://support.microsoft.com/en-us/office/correl-function-995dcef7-0c0a-4bed-a3fb-239d7b68ca92
+    @Test
+    void testMicrosoftExample() 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);
+        }
+    }
+
+    private HSSFWorkbook initWorkbook1() {
+        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, 15);
+        addRow(sheet, 5, 6, 17);
+        return wb;
+    }
+}