private static void Main(string[] args)
{
string filePath = "message.txt";
HufmannLetter[] letter = new HufmannLetter[5];
if (!FileExist(filePath))
{
CreateFile(filePath);
}
letter = ReadFile(filePath, letter);
CalculateProbabilty(letter);
double entropy = HufmannEntropy(letter);
Stack <List <HufmannLetter> > steps = BuildStack(letter);
BuildTree(steps);
double codeLength = CodeLength(letter);
double expectedCodeLength = ExpectedCodeLength(letter.Length);
foreach (var chars in letter)
{
Console.WriteLine("Char > {0} {1} {2} {3}", chars.LetterName, chars.LetterFrequency, chars.LetterProbability, chars.LetterPath);
}
Console.WriteLine("Entropy > " + entropy);
Console.WriteLine("L > " + codeLength);
Console.WriteLine("Expected Code Length > " + expectedCodeLength);
Console.ReadLine();
}
private static Stack <List <HufmannLetter> > BuildStack(HufmannLetter[] letters)
{
List <HufmannLetter> letterList = letters.ToList(); //List of letters
var dropLetterList = new List <HufmannLetter>(); //This list stores 3 letters, for example 3A 4B -> 7AB.
var steps = new Stack <List <HufmannLetter> >(); //Stack for building tree
while (true)
{
var lowestChar = letterList.Where(c => c.LetterFrequency == letterList.Min(x => x.LetterFrequency)).ElementAt(0); //minimum char in the list
dropLetterList.Add(lowestChar); //add it to the list
letterList.Remove(lowestChar); //remove from list of letters
if (dropLetterList.Count == 2)
{
string letterName = dropLetterList.ElementAt(0).LetterName + dropLetterList.ElementAt(1).LetterName;
int frequency = dropLetterList.ElementAt(0).LetterFrequency + dropLetterList.ElementAt(1).LetterFrequency;
HufmannLetter newLetter = new HufmannLetter(letterName, frequency); //create 7AB
dropLetterList.Add(newLetter); //add to droplist
letterList.Add(newLetter); //add to main letter list
steps.Push(new List <HufmannLetter>(dropLetterList));
dropLetterList.Clear();
if (letterList.Count == 1) //if list stores only one char (ABCDE). Finished
{
break;
}
}
}
return(steps);
}
public Node(HufmannLetter nodeName)
{
ByteOfPath = "";
Letter = nodeName;
Left = null;
Right = null;
Childrens = new List <Node>();
}
private static HufmannLetter[] ReadFile(string filePath, HufmannLetter[] letter)
{
string message = File.ReadAllText(filePath, Encoding.UTF8);
int differentCharNumber = letter.Length;
var letters = message.ToCharArray().GroupBy(x => x).Where(y => y.Any()).Select(z => new { charName = z.Key, charCount = z.Count() });
for (int i = 0; i < differentCharNumber; i++)
{
// ReSharper disable once PossibleMultipleEnumeration
var lettersAndFrequency = letters.ElementAt(i);
letter[i] = new HufmannLetter(lettersAndFrequency.charName + "", lettersAndFrequency.charCount);
}
return(letter);
}
private static void BuildTree(Stack <List <HufmannLetter> > letters)
{
HuffmanTree tree = new HuffmanTree();
tree.Insert(letters.Peek()[2], 0, null); //ROOT
while (letters.Count != 0)
{
HufmannLetter parent = letters.Peek()[2]; //2A and 3D 's parent is 5AD
for (int i = letters.Peek().Count - 2; i >= 0; i--)
{
tree.Insert(letters.Peek()[i], i, parent); //if i =0, left child, else right child. Parent 5AD
}
letters.Pop();
}
TreePrinter btr = new TreePrinter(); //Print the tree
btr.Print(tree.Root);
Console.WriteLine();
}
