Stats.cs revision 324c4644fee44b9898524c09511bd33c3f12e2df 
1/*
2 * [The "BSD licence"]
3 * Copyright (c) 2005-2008 Terence Parr
4 * All rights reserved.
5 *
6 * Conversion to C#:
7 * Copyright (c) 2008-2009 Sam Harwell, Pixel Mine, Inc.
8 * All rights reserved.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 3. The name of the author may not be used to endorse or promote products
19 *    derived from this software without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
22 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
23 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
24 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
26 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
30 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 */
32
33namespace Antlr.Runtime.Misc {
34    using System.Collections.Generic;
35    using Antlr.Runtime.JavaExtensions;
36
37    using Math = System.Math;
38
39    /** <summary>Stats routines needed by profiler etc...</summary>
40     *
41     *  <remarks>
42     *  note that these routines return 0.0 if no values exist in the X[]
43     *  which is not "correct", but it is useful so I don't generate NaN
44     *  in my output
45     *  </remarks>
46     */
47    public class Stats {
48        public const string ANTLRWORKS_DIR = "antlrworks";
49
50        /** <summary>Compute the sample (unbiased estimator) standard deviation following:</summary>
51         *
52         *  <remarks>
53         *  Computing Deviations: Standard Accuracy
54         *  Tony F. Chan and John Gregg Lewis
55         *  Stanford University
56         *  Communications of ACM September 1979 of Volume 22 the ACM Number 9
57         *
58         *  The "two-pass" method from the paper; supposed to have better
59         *  numerical properties than the textbook summation/sqrt.  To me
60         *  this looks like the textbook method, but I ain't no numerical
61         *  methods guy.
62         *  </remarks>
63         */
64        public static double Stddev(int[] X) {
65            int m = X.Length;
66            if (m <= 1) {
67                return 0;
68            }
69            double xbar = EnumerableExtensions.Average(X);
70            double s2 = 0.0;
71            for (int i = 0; i < m; i++) {
72                s2 += (X[i] - xbar) * (X[i] - xbar);
73            }
74            s2 = s2 / (m - 1);
75            return Math.Sqrt(s2);
76        }
77        public static double Stddev(List<int> X) {
78            int m = X.Count;
79            if (m <= 1) {
80                return 0;
81            }
82            double xbar = EnumerableExtensions.Average(X);
83            double s2 = 0.0;
84            for (int i = 0; i < m; i++) {
85                s2 += (X[i] - xbar) * (X[i] - xbar);
86            }
87            s2 = s2 / (m - 1);
88            return Math.Sqrt(s2);
89        }
90
91#if DEBUG
92        /** <summary>Compute the sample mean</summary> */
93        [System.Obsolete]
94        public static double avg(int[] X) {
95            return EnumerableExtensions.Average(EnumerableExtensions.DefaultIfEmpty(X, 0));
96        }
97
98        [System.Obsolete]
99        public static int min(int[] X) {
100            return EnumerableExtensions.Min(EnumerableExtensions.DefaultIfEmpty(X, int.MaxValue));
101        }
102
103        [System.Obsolete]
104        public static int max(int[] X) {
105            return EnumerableExtensions.Max(EnumerableExtensions.DefaultIfEmpty(X, int.MinValue));
106        }
107
108        [System.Obsolete]
109        public static int sum(int[] X) {
110            return EnumerableExtensions.Sum(X);
111        }
112#endif
113
114        public static void WriteReport(string filename, string data) {
115            string absoluteFilename = GetAbsoluteFileName(filename);
116
117            System.IO.Directory.CreateDirectory(System.IO.Path.GetDirectoryName(absoluteFilename));
118            System.IO.File.AppendAllText(absoluteFilename, data);
119        }
120
121        public static string GetAbsoluteFileName(string filename) {
122            string personalFolder = System.Environment.GetFolderPath(System.Environment.SpecialFolder.Personal);
123            return personalFolder + System.IO.Path.DirectorySeparatorChar +
124                        ANTLRWORKS_DIR + System.IO.Path.DirectorySeparatorChar +
125                        filename;
126        }
127    }
128}
129