double GetEntropy()
{
ProcessHook.reportStatus("HERE");
if (!File.Exists(filename))
{
return(-1);
}
ProcessHook.reportStatus("and here HERE");
ExamineChunk(filename);
ProcessHook.reportStatus("and also HERE");
// Reset values
overalEntropy = 0;
probabilityDict = new Dictionary <byte, double>();
foreach (KeyValuePair <byte, int> entry in distributionDict)
{
// Probability = Freq of symbol / # symbols examined thus far
probabilityDict.Add(
entry.Key,
(double)distributionDict[entry.Key] / (double)dataSize
);
}
foreach (KeyValuePair <byte, double> entry in probabilityDict)
{
// Entropy = probability * Log2(1/probability)
overalEntropy += entry.Value * Math.Log((1 / entry.Value), 2);
}
return(overalEntropy);
}
/****************************************
*
* private helper functions
*
* *************************************/
private static void reportEvent(string functionName, params string[] args)
{
StringBuilder sb = new StringBuilder();
sb.Append(args[0]);
for (int i = 1; i < args.Length; i++)
{
sb.Append(argsDemiliter);
sb.Append(args[i]);
}
ProcessHook.enqueueEvent(functionName, sb.ToString());
}
public void ExamineChunk(string filename)
{
//System.IO.FileStream file = new System.IO.FileStream(filename, FileMode.Open);
int actualRead = 0;
const int CHUNK_SIZE = 1024;
byte[] buffer = new byte[CHUNK_SIZE];
distributionDict = new Dictionary <byte, int>();
FileReader fr = new FileReader();
if (fr.Open(filename))
{
// Assume that an ASCII file is being read.
System.Text.ASCIIEncoding Encoding = new System.Text.ASCIIEncoding();
do
{
actualRead = fr.Read(buffer, 0, buffer.Length);
//string content = Encoding.GetString(buffer, 0, actualRead);
//System.Console.Write("{0}", content);
for (int i = 0; i < actualRead; ++i)
{
byte bite = buffer[i];
if (!distributionDict.ContainsKey(bite))
{
distributionDict.Add(bite, 1);
}
else
{
}
dataSize++;
}
} while (actualRead > 0);
fr.Close();
}
ProcessHook.reportStatus(Marshal.GetExceptionForHR(Marshal.GetHRForLastWin32Error()).ToString());
/*
* while ((actualRead = file.Read(buffer, 0 ,CHUNK_SIZE)) != 0)
* {
* for (int i = 0; i<actualRead; ++i)
* {
*
* byte bite = buffer[i];
* if (!distributionDict.ContainsKey(bite))
* {
* distributionDict.Add(bite, 1);
* }
* else
* {
* distributionDict[bite]++;
* }
* dataSize++;
* }
*
* }
*
* file.Close();
*/
}
