support blank cells in correl function

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1901683 13f79535-47bb-0310-9956-ffa450edef68

poi/src/main/java/org/apache/poi/ss/formula/functions/Correl.java

@@ -29,6 +29,9 @@ import org.apache.poi.ss.formula.eval.RefEval;
 import org.apache.poi.ss.formula.eval.StringValueEval;
 import org.apache.poi.ss.formula.eval.ValueEval;
 
+import java.util.Arrays;
+import java.util.List;
+
 /**
  * Implementation for Excel CORREL() function.
  * <p>
@@ -50,22 +53,34 @@ public class Correl extends Fixed2ArgFunction {
     @Override
     public ValueEval evaluate(int srcRowIndex, int srcColumnIndex, ValueEval arg0, ValueEval arg1) {
         try {
+            final List<DoubleList> arrays = getNumberArrays(arg0, arg1);
             final PearsonsCorrelation pc = new PearsonsCorrelation();
             final double correl = pc.correlation(
-                    getNumberArray(arg0), getNumberArray(arg1));
+                    arrays.get(0).toArray(), arrays.get(1).toArray());
             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 List<DoubleList> getNumberArrays(ValueEval operand0, ValueEval operand1) throws EvaluationException {
+        double[] retval0 = collectValuesWithBlanks(operand0).toArray();
+        double[] retval1 = collectValuesWithBlanks(operand1).toArray();
+        DoubleList filtered0 = new DoubleList();
+        DoubleList filtered1 = new DoubleList();
+        for (int i = 0; i < retval0.length; i++) {
+            if (Double.isNaN(retval0[i]) || Double.isNaN(retval1[i])) {
+                //ignore
+            } else {
+                filtered0.add(retval0[i]);
+                filtered1.add(retval1[i]);
+            }
+        }
+        return Arrays.asList(filtered0, filtered1);
     }
 
-    private void collectValues(ValueEval operand, DoubleList temp) throws EvaluationException {
+    private DoubleList collectValuesWithBlanks(ValueEval operand) throws EvaluationException {
+        DoubleList doubleList = new DoubleList();
         if (operand instanceof ThreeDEval) {
             ThreeDEval ae = (ThreeDEval) operand;
             for (int sIx = ae.getFirstSheetIndex(); sIx <= ae.getLastSheetIndex(); sIx++) {
@@ -74,11 +89,16 @@ public class Correl extends Fixed2ArgFunction {
                 for (int rrIx = 0; rrIx < height; rrIx++) {
                     for (int rcIx = 0; rcIx < width; rcIx++) {
                         ValueEval ve = ae.getValue(sIx, rrIx, rcIx);
-                        collectValue(ve, temp);
+                        Double d = collectValue(ve);
+                        if (d == null) {
+                            doubleList.add(Double.NaN);
+                        } else {
+                            doubleList.add(d.doubleValue());
+                        }
                     }
                 }
             }
-            return;
+            return doubleList;
         }
         if (operand instanceof TwoDEval) {
             TwoDEval ae = (TwoDEval) operand;
@@ -87,46 +107,54 @@ public class Correl extends Fixed2ArgFunction {
             for (int rrIx = 0; rrIx < height; rrIx++) {
                 for (int rcIx = 0; rcIx < width; rcIx++) {
                     ValueEval ve = ae.getValue(rrIx, rcIx);
-                    collectValue(ve, temp);
+                    Double d = collectValue(ve);
+                    if (d == null) {
+                        doubleList.add(Double.NaN);
+                    } else {
+                        doubleList.add(d.doubleValue());
+                    }
                 }
             }
-            return;
+            return doubleList;
         }
         if (operand instanceof RefEval) {
             RefEval re = (RefEval) operand;
             for (int sIx = re.getFirstSheetIndex(); sIx <= re.getLastSheetIndex(); sIx++) {
-                collectValue(re.getInnerValueEval(sIx), temp);
+                Double d = collectValue(re.getInnerValueEval(sIx));
+                if (d == null) {
+                    doubleList.add(Double.NaN);
+                } else {
+                    doubleList.add(d.doubleValue());
+                }
             }
-            return;
+            return doubleList;
+        }
+        Double d = collectValue(operand);
+        if (d == null) {
+            doubleList.add(Double.NaN);
+        } else {
+            doubleList.add(d.doubleValue());
         }
-        collectValue(operand, temp);
+        return doubleList;
     }
 
-    private void collectValue(ValueEval ve, DoubleList temp) throws EvaluationException {
+    private Double collectValue(ValueEval ve) 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;
+            return ne.getNumberValue();
         }
         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;
+            return OperandResolver.parseDouble(s);
         }
         if (ve instanceof ErrorEval) {
             throw new EvaluationException((ErrorEval) ve);
         }
         if (ve == BlankEval.instance) {
-            temp.add(0.0);
-            return;
+            return null;
         }
         throw new RuntimeException("Invalid ValueEval type passed for conversion: ("
                 + ve.getClass() + ")");

poi/src/main/java/org/apache/poi/ss/formula/functions/DoubleList.java

@@ -46,4 +46,8 @@ final class DoubleList {
         _array[_count] = value;
         _count++;
     }
+
+    public int getLength() {
+        return _count;
+    }
 }

poi/src/test/java/org/apache/poi/ss/formula/functions/TestCorrel.java

@@ -36,8 +36,8 @@ 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()) {
+    void testMicrosoftExample1() throws IOException {
+        try (HSSFWorkbook wb = initWorkbook1(false)) {
             HSSFSheet sheet = wb.getSheetAt(0);
             HSSFRow row = sheet.getRow(0);
             HSSFCell cell = row.createCell(100);
@@ -46,14 +46,29 @@ final class TestCorrel {
         }
     }
 
-    private HSSFWorkbook initWorkbook1() {
+    @Test
+    void testBlankValue() throws IOException {
+        try (HSSFWorkbook wb = initWorkbook1(true)) {
+            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);
+        }
+    }
+
+    private HSSFWorkbook initWorkbook1(boolean blankRow4) {
         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);
+        if (blankRow4) {
+            addRow(sheet, 4, 5);
+        } else {
+            addRow(sheet, 4, 5, 15);
+        }
         addRow(sheet, 5, 6, 17);
         return wb;
     }