1 | /* Copyright (C) 2011 Jan Källman
|
---|
2 | *
|
---|
3 | * This library is free software; you can redistribute it and/or
|
---|
4 | * modify it under the terms of the GNU Lesser General Public
|
---|
5 | * License as published by the Free Software Foundation; either
|
---|
6 | * version 2.1 of the License, or (at your option) any later version.
|
---|
7 |
|
---|
8 | * This library is distributed in the hope that it will be useful,
|
---|
9 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
|
---|
10 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
|
---|
11 | * See the GNU Lesser General Public License for more details.
|
---|
12 | *
|
---|
13 | * The GNU Lesser General Public License can be viewed at http://www.opensource.org/licenses/lgpl-license.php
|
---|
14 | * If you unfamiliar with this license or have questions about it, here is an http://www.gnu.org/licenses/gpl-faq.html
|
---|
15 | *
|
---|
16 | * All code and executables are provided "as is" with no warranty either express or implied.
|
---|
17 | * The author accepts no liability for any damage or loss of business that this product may cause.
|
---|
18 | *
|
---|
19 | * Code change notes:
|
---|
20 | *
|
---|
21 | * Author Change Date
|
---|
22 | *******************************************************************************
|
---|
23 | * Mats Alm Added 2013-12-03
|
---|
24 | *******************************************************************************/
|
---|
25 | using System;
|
---|
26 | using System.Collections.Generic;
|
---|
27 | using System.Linq;
|
---|
28 | using System.Text;
|
---|
29 | using OfficeOpenXml.FormulaParsing.Exceptions;
|
---|
30 | using MathObj = System.Math;
|
---|
31 | using OfficeOpenXml.FormulaParsing.ExpressionGraph;
|
---|
32 |
|
---|
33 | namespace OfficeOpenXml.FormulaParsing.Excel.Functions.Math
|
---|
34 | {
|
---|
35 | public class Stdev : HiddenValuesHandlingFunction
|
---|
36 | {
|
---|
37 | public override CompileResult Execute(IEnumerable<FunctionArgument> arguments, ParsingContext context)
|
---|
38 | {
|
---|
39 | ValidateArguments(arguments, 1);
|
---|
40 | var values = ArgsToDoubleEnumerable(arguments, context, false);
|
---|
41 | return CreateResult(StandardDeviation(values), DataType.Decimal);
|
---|
42 | }
|
---|
43 |
|
---|
44 | private double StandardDeviation(IEnumerable<double> values)
|
---|
45 | {
|
---|
46 | double ret = 0;
|
---|
47 | if (values.Any())
|
---|
48 | {
|
---|
49 | var nValues = values.Count();
|
---|
50 | if(nValues == 1) throw new ExcelErrorValueException(eErrorType.Div0);
|
---|
51 | //Compute the Average
|
---|
52 | double avg = values.Average();
|
---|
53 | //Perform the Sum of (value-avg)_2_2
|
---|
54 | double sum = values.Sum(d => MathObj.Pow(d - avg, 2));
|
---|
55 | //Put it all together
|
---|
56 | ret = MathObj.Sqrt(Divide(sum, (values.Count() - 1)));
|
---|
57 | }
|
---|
58 | return ret;
|
---|
59 | }
|
---|
60 |
|
---|
61 | }
|
---|
62 | }
|
---|