EPPlus/FormulaParsing/Excel/Functions/Math/Median.cs

/* Copyright (C) 2011  Jan Källman
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.

 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU Lesser General Public License for more details.
 *
 * The GNU Lesser General Public License can be viewed at http://www.opensource.org/licenses/lgpl-license.php
 * If you unfamiliar with this license or have questions about it, here is an http://www.gnu.org/licenses/gpl-faq.html
 *
 * All code and executables are provided "as is" with no warranty either express or implied.
 * The author accepts no liability for any damage or loss of business that this product may cause.
 *
 * Code change notes:
 *
 * Author							Change						Date
 *******************************************************************************
 * Mats Alm   		                Added		                2015-01-10
 *******************************************************************************/

using System;
using System.Collections.Generic;
using System.Linq;
using OfficeOpenXml.FormulaParsing.ExpressionGraph;

namespace OfficeOpenXml.FormulaParsing.Excel.Functions.Math;

public class Median : ExcelFunction {
  public override CompileResult Execute(
      IEnumerable<FunctionArgument> arguments,
      ParsingContext context) {
    var nums = ArgsToDoubleEnumerable(arguments, context);
    var arr = nums.ToArray();
    Array.Sort(arr);
    ThrowExcelErrorValueExceptionIf(() => arr.Length == 0, eErrorType.Num);
    double result;
    if (arr.Length % 2 == 1) {
      result = arr[arr.Length / 2];
    } else {
      var startIndex = arr.Length / 2 - 1;
      result = (arr[startIndex] + arr[startIndex + 1]) / 2d;
    }
    return CreateResult(result, DataType.Decimal);
  }
}