POI 62373, Support for FREQUENCY function

main/SS/Formula/Eval/FunctionEval.cs

@@ -334,7 +334,7 @@ private static Function[] ProduceFunctions()
             retval[247] = new NotImplementedFunction("DB"); // DB
             retval[248] = new NotImplementedFunction("PAUSE"); // PAUSE
             retval[250] = new NotImplementedFunction("RESUME"); // RESUME
-            retval[252] = new NotImplementedFunction("FREQUENCY"); // FREQUENCY
+            retval[252] = Frequency.Instance; // FREQUENCY
             retval[253] = new NotImplementedFunction("AddTOOLBAR"); // AddTOOLBAR
             retval[254] = new NotImplementedFunction("DELETETOOLBAR"); // DELETETOOLBAR
             retval[FunctionID.EXTERNAL_FUNC] = null; // ExternalFunction is a FreeREfFunction

main/SS/Formula/Functions/Frequency.cs

@@ -0,0 +1,104 @@
+/* ====================================================================
+   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.
+==================================================================== */
+
+
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.IO;
+using System.Text;
+
+namespace NPOI.SS.Formula.Functions
+{
+    using NPOI.SS.Formula;
+    using NPOI.SS.Formula.Eval;
+    using NPOI.Util;
+    using NPOI.Util.ArrayExtensions;
+
+
+    /// <summary>
+    /// <para>
+    /// Implementation of Excel 'Analysis ToolPak' function FREQUENCY()<br>
+    /// Returns a frequency distribution as a vertical array
+    /// </para>
+    /// <para>
+    /// <b>Syntax</b><br>
+    /// <b>FREQUENCY</b>(<b>data_array</b>, <b>bins_array</b>)
+    /// </para>
+    /// <para>
+    /// <b>data_array</b> Required. An array of or reference to a Set of values for which you want to count frequencies.
+    /// If data_array contains no values, FREQUENCY returns an array of zeros.<br>
+    /// <b>bins_array</b> Required. An array of or reference to intervals into which you want to group the values in data_array.
+    /// If bins_array contains no values, FREQUENCY returns the number of elements in data_array.<br>
+    /// </para>
+    /// </summary>
+    public class Frequency : Fixed2ArgFunction
+    {
+        public static  Function Instance = new Frequency();
+
+        private Frequency()
+        {
+            // enforce singleton
+        }
+        public override ValueEval Evaluate(int srcRowIndex, int srcColumnIndex, ValueEval arg0, ValueEval arg1)
+        {
+            MatrixFunction.MutableValueCollector collector = new MatrixFunction.MutableValueCollector(false, false);
+
+            double[] values;
+            double[] bins;
+            try
+            {
+                values = collector.collectValues(arg0);
+                bins = collector.collectValues(arg1);
+            }
+            catch(EvaluationException e)
+            {
+                return e.GetErrorEval();
+            }
+
+            // can bins be not sorted?
+            //bins = Arrays.stream(bins).sorted().distinct().ToArray();
+
+            int[] histogram = Histogram(values, bins);
+
+            NumberEval[] result = new NumberEval[histogram.Length]; // Arrays.Stream(histogram).boxed().map(NumberEval::new).ToArray(NumberEval[]::new);
+            for(var i = 0; i<histogram.Length; i++)
+            {
+                result[i] = new NumberEval(histogram[i]);
+            }
+            return new CacheAreaEval(srcRowIndex, srcColumnIndex,
+                    srcRowIndex + result.Length - 1, srcColumnIndex, result);
+        }
+
+        public static int FindBin(double value, double[] bins)
+        {
+            int idx = Array.BinarySearch(bins, value);
+            return idx >= 0 ? idx + 1 : -idx;
+        }
+
+        public static int[] Histogram(double[] values, double[] bins)
+        {
+            int[] histogram = new int[bins.Length + 1];
+            foreach(double val in values)
+            {
+                histogram[FindBin(val, bins) - 1]++;
+            }
+            return histogram;
+        }
+    }
+}
+

testcases/main/SS/Formula/Functions/TestFrequency.cs

@@ -0,0 +1,108 @@
+/* ====================================================================
+   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.
+==================================================================== */
+
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.IO;
+using System.Text;
+
+namespace NPOI.SS.Formula.Functions
+{
+    using NPOI.HSSF.UserModel;
+    using NPOI.SS.UserModel;
+    using NPOI.SS.Util;
+    using NPOI.Util;
+    using NPOI.Util.ArrayExtensions;
+    using NUnit.Framework;
+    using static NPOI.SS.Formula.Functions.Frequency;
+
+    /// <summary>
+    /// Testcase for the function FREQUENCY(data, bins)
+    /// </summary>
+    /// <remarks>
+    /// @author Yegor Kozlov
+    /// </remarks>
+    [TestFixture]
+    public class TestFrequency
+    {
+
+        [Test]
+        public void TestHistogram()
+        {
+
+            Assert.IsTrue(Arrays.Equals(new int[] { 3, 2, 2, 0, 1, 1 },
+                    Histogram(
+                            new double[] { 11, 12, 13, 21, 29, 36, 40, 58, 69 },
+                            new double[] { 20, 30, 40, 50, 60 })
+            ));
+
+            Assert.IsTrue(Arrays.Equals(new int[] { 1, 1, 1, 1, 1, 0 },
+                    Histogram(
+                            new double[] { 20, 30, 40, 50, 60 },
+                            new double[] { 20, 30, 40, 50, 60 })
+
+            ));
+
+            Assert.IsTrue(Arrays.Equals(new int[] { 2, 3 },
+                    Histogram(
+                            new double[] { 20, 30, 40, 50, 60 },
+                            new double[] { 30 })
+
+            ));
+        }
+
+        [Test]
+        public void TestEvaluate()
+        {
+            IWorkbook wb = new HSSFWorkbook();
+            IFormulaEvaluator evaluator = wb.GetCreationHelper().CreateFormulaEvaluator();
+
+            int[] data = {1, 1, 2, 3, 4, 4, 5, 7, 8, 9, 9, 11, 3, 5, 8};
+            int[] bins = {3, 6, 9};
+            ISheet sheet = wb.CreateSheet();
+            IRow dataRow = sheet.CreateRow(0); // A1:O1
+            for(int i = 0; i < data.Length; i++)
+            {
+                dataRow.CreateCell(i).SetCellValue(data[i]);
+            }
+            IRow binsRow = sheet.CreateRow(1);
+            for(int i = 0; i < bins.Length; i++)
+            { 
+                // A2:C2
+                binsRow.CreateCell(i).SetCellValue(bins[i]);
+            }
+            IRow fmlaRow = sheet.CreateRow(2);
+            ICellRange<ICell> arrayFmla = sheet.SetArrayFormula("FREQUENCY(A1:O1,A2:C2)", CellRangeAddress.ValueOf("A3:A6"));
+            ICell b3 = fmlaRow.CreateCell(1); // B3
+            b3.SetCellFormula("COUNT(FREQUENCY(A1:O1,A2:C2))"); // frequency returns a vertical array of bins+1
+
+            ICell c3 = fmlaRow.CreateCell(2);
+            c3.SetCellFormula("SUM(FREQUENCY(A1:O1,A2:C2))"); // sum of the frequency bins should add up to the number of data values
+
+            Assert.AreEqual(5, (int) evaluator.Evaluate(arrayFmla.FlattenedCells[0]).NumberValue);
+            Assert.AreEqual(4, (int) evaluator.Evaluate(arrayFmla.FlattenedCells[1]).NumberValue);
+            Assert.AreEqual(5, (int) evaluator.Evaluate(arrayFmla.FlattenedCells[2]).NumberValue);
+            Assert.AreEqual(1, (int) evaluator.Evaluate(arrayFmla.FlattenedCells[3]).NumberValue);
+
+            Assert.AreEqual(4, (int) evaluator.Evaluate(b3).NumberValue);
+            Assert.AreEqual(15, (int) evaluator.Evaluate(c3).NumberValue);
+
+        }
+    }
+}
+