// This method is to encode text based on the this tree
public byte[] Encode(string text)
{
// a local recursive function to convert a character into an array of bits based on the root huffman node
BitArray convertToBitarray(HuffmanNode n, char c)
{
// if we found a leaf, return the code
if (n.IsLeaf)
{
return(n.Code);
}
else
{
// Call this function again, but with either the left or the right
if (n.LeftChildNode.Symbol.Contains(c))
{
return(convertToBitarray(n.LeftChildNode, c));
}
else if (n.RightChildNode.Symbol.Contains(c))
{
return(convertToBitarray(n.RightChildNode, c));
}
else
{
throw new Exception("something went wrong when converting the tree");
}
}
}
// Init list for the bits
BitList bits = new BitList();
// make the text into a character array, and loop tought it
text.ToCharArray().ToList().ForEach(x => {
// Use the recursive function from before to calculate the bits
// Add the bits to the list of bits
bits.AddBitArray(convertToBitarray(Root, x));
});
// We add a 1 to the list
bits.Add(true);
// We fill the list up with 0's, until it is divisible by 8
while (bits.Count % 8 != 0)
{
bits.Add(false);
}
// Create the array of bytes
byte[] bytes = new byte[bits.Count / 8];
// Copy the array of bits to the array of bytes
bits.ToBitArray().CopyTo(bytes, 0);
// Return the bytes
return(bytes);
}
// This method is to encode text based on the this tree
// Denne funktion enkoder tekst baseret på det foregående træ
public byte[] Encode(string text)
{
// a local recursive function to convert a character into an array of bits based on the root huffman node
// En lokal rekursiv funktion for at konvertere et symbol om til et array af bits baseret på Hoffman nodens rod
BitArray convertToBitarray(HuffmanNode n, char c)
{
// if we found a leaf, return the code
// Hvis det er et blad, returnerer koden
if (n.IsLeaf)
{
return(n.Code);
}
else
{
// Call this function again, but with either the left or the right
// Kald denne funktion igen, men med enten højre eller venstre
if (n.LeftChildNode.Symbol.Contains(c))
{
return(convertToBitarray(n.LeftChildNode, c));
}
else if (n.RightChildNode.Symbol.Contains(c))
{
return(convertToBitarray(n.RightChildNode, c));
}
else
{
throw new Exception("something went wrong when converting the tree");
}
}
}
// Init list for the bits
// Ny liste for bitsene
BitList bits = new BitList();
// make the text into a character array, and loop trough it
// Lav teksten om til et symbol-array, og loop igennem det
text.ToCharArray().ToList().ForEach(x => {
// Use the recursive function from before to calculate the bits
// Add the bits to the list of bits
// Der bruges den rekursive funktion fra før til at udregne bitsene
// Tilføj bitsene til listen over bits
bits.AddBitArray(convertToBitarray(Root, x));
});
// We add a 1 to the list
// Der tilføjes et 1 til listen
bits.Add(true);
// We fill the list up with 0's, until it is divisible by 8
// Listen fyldes op med 0'er, indtil at den kan divideres med 8
while (bits.Count % 8 != 0)
{
bits.Add(false);
}
// Create the array of bytes
// Der laves et array over bytes
byte[] bytes = new byte[bits.Count / 8];
// Copy the array of bits to the array of bytes
// array over bits indsættes ind i array over bytes
bits.ToBitArray().CopyTo(bytes, 0);
// Return the bytes
// Returner bytes
return(bytes);
}
// this method creates a tree based on text
public static HuffmanTree CreateFromText(string text)
{
// the list that we wanna fill up with nodes
List <HuffmanNode> nodeList = new List <HuffmanNode>();
// all the characters from the text
char[] characters = text.ToCharArray();
// loop thought the characters
for (int i = 0; i < characters.Length; i++)
{
// the character as a string
string read = characters[i].ToString();
// has the node already been created?
if (nodeList.Exists(x => x.Symbol == read))
{
// If is yes, find the index of the Node and increase the frequency of the Node.
nodeList[nodeList.FindIndex(y => y.Symbol == read)].Frequency++;
}
else
{
// If is no, create a new node and add to the List of Nodes
nodeList.Add(new HuffmanNode(read));
}
}
// sort them, this is done based on frequency because of IComparable<HuffmanNode>.CompareTo
nodeList.Sort();
// loop thought them, until only one is left
while (nodeList.Count > 1)
{
// Get the node of the first index of List, this is the one with the lowest frequency
HuffmanNode node1 = nodeList[0];
// and delete it.
nodeList.RemoveAt(0);
// do the same thing again
HuffmanNode node2 = nodeList[0];
nodeList.RemoveAt(0);
// make a parant node with node1 and node2 and the left and right child nodes
nodeList.Add(new HuffmanNode(node1, node2));
// and sort it again according to frequency.
nodeList.Sort();
}
// create a tree based on the remaining root node
HuffmanTree tree = new HuffmanTree(nodeList[0]);
// this is a recursive function to set the binary code of every leaf node
void setCodeToTheTree(HuffmanNode Nodes, BitArray code = null)
{
// if the current code is not set, set it to an empty BitArray
if (code == null)
{
code = new BitArray(new bool[] { });
}
// if the code is empty do nothing
if (Nodes == null)
{
return;
}
// if there is no left node and right node, then set the code based on the current code
if (Nodes.LeftChildNode == null && Nodes.RightChildNode == null)
{
Nodes.Code = code;
return;
}
// create a bitlist for the left node
BitList left = BitList.Parse(code);
// add false for the left side
left.Add(false);
// call this function recursively, with the left bitlist and the left side node
setCodeToTheTree(Nodes.LeftChildNode, left.ToBitArray());
// create a bitlist for the right node
BitList right = BitList.Parse(code);
// add true for the right side
right.Add(true);
// call the function recursively, with the right bitlist and the right side node
setCodeToTheTree(Nodes.RightChildNode, right.ToBitArray());
}
// call the recursive function
setCodeToTheTree(tree.Root);
// the tree
return(tree);
}
// this method creates a tree based on text
// Denne funktion laver et træ baseret på tekst
public static HuffmanTree CreateFromText(string text)
{
// the list that we wanna fill up with nodes
// Listen der skal fyldes med noder
List <HuffmanNode> nodeList = new List <HuffmanNode>();
// all the characters from the text
// Alle symbolerne fra teksten
char[] characters = text.ToCharArray();
// loop thought the characters
// Gentag igennem symbolerne
for (int i = 0; i < characters.Length; i++)
{
// the character as a string
// Symbolerne som strenge
string read = characters[i].ToString();
// has the node already been created?
// Er noden allerede blevet skabt?
if (nodeList.Exists(x => x.Symbol == read))
{
// If is yes, find the index of the Node and increase the frequency of the Node.
// Hvis ja, find indekset for noden og øg frekvensen for node
nodeList[nodeList.FindIndex(y => y.Symbol == read)].Frequency++;
}
else
{
// If is no, create a new node and add to the List of Nodes
// Hvis nej, skab en ny node og tilføj den til listen over node
nodeList.Add(new HuffmanNode(read));
}
}
// sort them, this is done based on frequency because of IComparable<HuffmanNode>.CompareTo
// Sorter dem, dette gøres baseret på frekvens fordi at IComparable<HuffmanNode>.CompareTo
nodeList.Sort();
// loop thought them, until only one is left
// Kør igennem dem alle sammen indtil der kun er en tilbage
while (nodeList.Count > 1)
{
// Get the node of the first index of List, this is the one with the lowest frequency
// Få noden for det første indeks af Listen, dette er den med den laveste frekvens
HuffmanNode node1 = nodeList[0];
// and delete it.
// Fjern den
nodeList.RemoveAt(0);
// do the same thing again
// Gør det samme igen
HuffmanNode node2 = nodeList[0];
nodeList.RemoveAt(0);
// make a parant node with node1 and node2 and the left and right child nodes
// Lav en parent-node med node1 og node1 og de venstre og højre child-noder
nodeList.Add(new HuffmanNode(node1, node2));
// and sort it again according to frequency.
// Og sorter det igen efter frekvens
nodeList.Sort();
}
// create a tree based on the remaining root node
// Lav et træ baseret på den tilbageværende rod-node
HuffmanTree tree = new HuffmanTree(nodeList[0]);
// this is a recursive function to set the binary code of every leaf node
// Dette er en rekursiv funktion for at sætte den binære værdi for hvert blad
void setCodeToTheTree(HuffmanNode Nodes, BitArray code = null)
{
// if the current code is not set, set it to an empty BitArray
// Hvis den nuværende kode ikke er sat, sættes den til et tomt BitArray
if (code == null)
{
code = new BitArray(new bool[] { });
}
// if the code is empty do nothing
// Hvis koden er tom, gør intet
if (Nodes == null)
{
return;
}
// if there is no left node and right node, then set the code based on the current code
// Hvis der ikke er nogen venstre node, sæt koden baseret på den nuværende kode
if (Nodes.LeftChildNode == null && Nodes.RightChildNode == null)
{
Nodes.Code = code;
return;
}
// create a bitlist for the left node
// lav en bitliste for den venstre node
BitList left = BitList.Parse(code);
// add false for the left side
// tilføj false for den venstre side
left.Add(false);
// call this function recursively, with the left bitlist and the left side node
// Kald denne funktion rekursivt, med den venstre bitliste og den venstre node
setCodeToTheTree(Nodes.LeftChildNode, left.ToBitArray());
// create a bitlist for the right node
// Lav en bitliste for den højre node
BitList right = BitList.Parse(code);
// add true for the right side
// tilføj true for den højre side
right.Add(true);
// call the function recursively, with the right bitlist and the right side node
// Kald denne funktion rekursivt, med den højre bitliste og den højre node
setCodeToTheTree(Nodes.RightChildNode, right.ToBitArray());
}
// call the recursive function
// Kald den rekursive funktion
setCodeToTheTree(tree.Root);
// the tree
// Træet returneres
return(tree);
}