Statistics.cs

Description du code

Statistics.cs est un fichier du projet PhotoBrol.
Ce fichier est situé dans /var/www/bin/sniplets/bibliobrol/photobrol/.

Projet PhotoBrol :

Editeur d'images en CSharp.

Code source ou contenu du fichier

  1. using System;
  2. using System.Collections.Generic;
  3. using System.Text;
  4.  
  5. namespace be.gaudry.model.math
  6. {
  7. /// <summary>
  8. /// Set of statistics functions
  9. /// </summary>
  10. ///
  11. /// <remarks>The class represents collection of functions used
  12. /// in statistics</remarks>
  13. ///
  14. public class Statistics
  15. {
  16. /// <summary>
  17. /// Calculate mean value
  18. /// </summary>
  19. ///
  20. /// <param name="values">Histogram array</param>
  21. ///
  22. /// <returns>Returns mean value</returns>
  23. ///
  24. /// <remarks>The input array is treated as histogram, i.e. its
  25. /// indexes are treated as values of stochastic function, but
  26. /// array values are treated as "probabilities" (total amount of
  27. /// hits).</remarks>
  28. ///
  29. public static double Mean(int[] values)
  30. {
  31. int hits;
  32. int mean = 0;
  33. int total = 0;
  34.  
  35. // for all values
  36. for (int i = 0, n = values.Length; i < n; i++)
  37. {
  38. hits = values[i];
  39. // accumulate mean
  40. mean += i * hits;
  41. // accumalate total
  42. total += hits;
  43. }
  44. return (double)mean / total;
  45. }
  46.  
  47. /// <summary>
  48. /// Calculate standard deviation
  49. /// </summary>
  50. ///
  51. /// <param name="values">Histogram array</param>
  52. ///
  53. /// <returns>Returns value of standard deviation</returns>
  54. ///
  55. /// <remarks>The input array is treated as histogram, i.e. its
  56. /// indexes are treated as values of stochastic function, but
  57. /// array values are treated as "probabilities" (total amount of
  58. /// hits).</remarks>
  59. ///
  60. public static double StdDev(int[] values)
  61. {
  62. double mean = Mean(values);
  63. double stddev = 0;
  64. double centeredValue;
  65. int hits;
  66. int total = 0;
  67.  
  68. // for all values
  69. for (int i = 0, n = values.Length; i < n; i++)
  70. {
  71. hits = values[i];
  72. centeredValue = (double)i - mean;
  73.  
  74. // accumulate mean
  75. stddev += centeredValue * centeredValue * hits;
  76. // accumalate total
  77. total += hits;
  78. }
  79.  
  80. return System.Math.Sqrt(stddev / total);
  81. }
  82.  
  83. /// <summary>
  84. /// Calculate median value
  85. /// </summary>
  86. ///
  87. /// <param name="values">Histogram array</param>
  88. ///
  89. /// <returns>Returns value of median</returns>
  90. ///
  91. /// <remarks>The input array is treated as histogram, i.e. its
  92. /// indexes are treated as values of stochastic function, but
  93. /// array values are treated as "probabilities" (total amount of
  94. /// hits).</remarks>
  95. ///
  96. public static int Median(int[] values)
  97. {
  98. /*int total = 0, n = values.Length;
  99.  
  100.   // for all values
  101.   for (int i = 0; i < n; i++)
  102.   {
  103.   // accumalate total
  104.   total += values[i];
  105.   }
  106.  
  107.   int halfTotal = total / 2;
  108.   int median = 0, v = 0;
  109.  
  110.   // find median value
  111.   for (; median < n; median++)
  112.   {
  113.   v += values[median];
  114.   if (v >= halfTotal)
  115.   break;
  116.   }
  117.  
  118.   return median;*/
  119. Array.Sort(values);
  120. return values[((values.Length -1)/2)+1];
  121. }
  122.  
  123. /// <summary>
  124. /// Get range around median containing specified percentage of values
  125. /// </summary>
  126. ///
  127. /// <param name="values">Histogram array</param>
  128. /// <param name="percent">Values percentage around median</param>
  129. ///
  130. /// <returns>Returns the range which containes specifies percentage
  131. /// of values.</returns>
  132. ///
  133. public static IntRange GetRange(int[] values, double percent)
  134. {
  135. int total = 0, n = values.Length;
  136.  
  137. // for all values
  138. for (int i = 0; i < n; i++)
  139. {
  140. // accumalate total
  141. total += values[i];
  142. }
  143.  
  144. int min, max, hits;
  145. int h = (int)(total * (percent + (1 - percent) / 2));
  146.  
  147. // get range min value
  148. for (min = 0, hits = total; min < n; min++)
  149. {
  150. hits -= values[min];
  151. if (hits < h)
  152. break;
  153. }
  154. // get range max value
  155. for (max = n - 1, hits = total; max >= 0; max--)
  156. {
  157. hits -= values[max];
  158. if (hits < h)
  159. break;
  160. }
  161. return new IntRange(min, max);
  162. }
  163.  
  164. /// <summary>
  165. /// Calculate an entropy
  166. /// </summary>
  167. ///
  168. /// <param name="values">Histogram array</param>
  169. ///
  170. /// <returns>Returns entropy value</returns>
  171. ///
  172. /// <remarks>The input array is treated as histogram, i.e. its
  173. /// indexes are treated as values of stochastic function, but
  174. /// array values are treated as "probabilities" (total amount of
  175. /// hits).</remarks>
  176. ///
  177. public static double Entropy(int[] values)
  178. {
  179. int n = values.Length;
  180. int total = 0;
  181. double entropy = 0;
  182. double p;
  183.  
  184. // calculate total amount of hits
  185. for (int i = 0; i < n; i++)
  186. {
  187. total += values[i];
  188. }
  189.  
  190. // for all values
  191. for (int i = 0; i < n; i++)
  192. {
  193. // get item's probability
  194. p = (double)values[i] / total;
  195. // calculate entropy
  196. if (p != 0)
  197. entropy += (-p * System.Math.Log(p, 2));
  198. }
  199. return entropy;
  200. }
  201. }
  202. }

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Afficher le fichier .cs|.csStatistics.cs6.11 Ko31/10/2018 18:32:51-refusé-
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Document created the 30/10/2009, last modified the 26/10/2018
Source of the printed document:https://www.gaudry.be/en/cs-photobrol-source-rf-model/math//Statistics.cs.html

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