adharshkamath · October 30, 2019 01:34 · Oct 30, 2019
diff --git a/HuffmanEncDec.m b/HuffmanEncDec.m
@@ -0,0 +1,96 @@
+function [ codeword ] = huffman_encode( p )
+
+n=length(p);
+codeword=cell(1,n);
+X=zeros(n,n);
+temp=p;
+%%
+%Building the relationship matrix X.This matrix has all elements zero
+%except for few entries which are substituted with 10 or 11.Number 10 denotes this
+%entry is the minimum in the column and 11 indicates this is the second
+%minimum.the minimum is replaced by 100 and second minimum is replaced by
+%sum of the minimum and the second minimum.And processing for the next
+%column progresses
+for i=1:n-1
+    [~ ,l]=sort(temp);
+    X(l(1),i)=10;
+    X(l(2),i)=11;
+    temp(l(2))=temp(l(2))+temp(l(1));
+    temp(l(1))=100;
+end
+
+i=n-1;
+rows=find(X(:,i)==10);
+codeword(rows)=strcat(codeword(rows),'1');
+rows=find(X(:,i)==11);
+codeword(rows)=strcat(codeword(rows),'0');
+for i=n-2:-1:1
+    row11=find(X(:,i)==11);
+    row10=find(X(:,i)==10);
+    codeword(row10)=strcat(codeword(row11),'1');
+    codeword(row11)=strcat(codeword(row11),'0');
+end
+end
+
+
+function [symbols,probability] = char_hist(message)
+
+symbols=[];
+probability=[];
+n=length(message);
+i=1;
+while ~isempty(message)
+    [mode_char,no_occurrances]=mode(message);
+    symbols(i)=mode_char;
+    probability(i)=no_occurrances;
+    indices=find(message==mode_char);
+    message(indices)='';
+    i=i+1;
+end
+probability=probability/n;
+end
+
+
+function [msg] = huffman_decode(symb,code,bitstream)
+%Assuming code to be in cell format
+%n is the number of messages
+% maxlen is maximum length of code
+%Idea is simple.We are going to search for matching of bits until we reach
+%maximum length of the codeword or match is found.When a match between bit
+%or group of bits is found we notedown the corresponding symbol of the
+%group of bits.
+n=length(symb);
+lengths=[];
+for i=1:n
+    len=length(char(code(i)));
+    lengths=[lengths len];
+end
+maxlen=max(lengths);
+msg='';
+%bitstream length is denoted by streamlen
+streamlen=length(bitstream);
+i=1;
+while i<=streamlen
+    j=0;
+    while j<maxlen
+        c=bitstream(i:i+j);
+        ind=1;
+        while (ind<=n && ~isequal(char(code(ind)),c))
+            ind=ind+1;
+        end
+        if ind<=n
+            msg=[msg char(symb(ind))];
+            break
+        else j=j+1;
+        end
+    end
+    i=i+j+1;
+end
+
+
+function [message] = read_file(filename)
+fileId=fopen(filename,'r');
+message=fscanf(fileId,'%c');
+fclose(fileId);
+end
+