huffman.m

霍夫曼编译码

function huffman_en_decode()
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%董婷婷07120080，通信0705班
%说明：文件中使用的子函数参考了www.mathworks.com上的代码

%子函数功能说明：hufflen(S)               根据符号概率，计算霍夫曼编码长度
%                huffcode(HL,Display)     根据编码长度，得到二进制编码结果（按行存放）
%                hufftree(HL,HK)          建立霍夫曼树，用于解码
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%读入预编码数据文件%%%%%%%%%%%%%%%%%%%%%%%%%%
clc
clear;
f=fopen('poem.txt');                             
   if(f == -1)
       disp('can not open the file');
   else
       data = fread(f)';
   end
    disp('按任意键察看待编码数据'); 
    pause;
winopen('poem.txt');
s=size(data);

%%%%%%%%%%%%%%统计出现过的字符symbol,以及他们的出现次数num%%%%%%%%%%%%%%%%
symbol=zeros(1,256);
count=zeros(1,256);
symbol(1,1)=data(1,1);

for i=1:s(1,2)
    for j=1:100
        if(symbol(1,j)==0 )
            symbol(1,j)=data(1,i);
            count(1,j)=1;
            break;
        end
        if(symbol(1,j)==data(1,i))
            count(1,j)=count(1,j)+1;
            break;
        end
    end
end   
    symbol=char(symbol);
    for i=1:100
        if count(i)==0
        else
            count1(i)=count(i);
            symbol1(i)=symbol(i);
        end
    end
    count=count(:);
    symbol=symbol(:);
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    

%%%%%%%%%%%%%%%%%%%%%%%%%编码(压缩)%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   ind=find(count>0);                  %得到大于零的元素索引index
   cou=count(ind);
   ind=find(symbol>0);
   sym=symbol(ind);

   hl=hufflen(cou);                     %hl_every element coding length
   hk= huffcode(hl);                   %hk_every element code

   disp('按任意键察看单个字符huffman编码结果');
    pause;
    for i=1:length(symbol1)
        disp('符号')
        disp(symbol1(i));
        disp('出现的次数')
        disp(count1(i));
        disp('编码结果：')
        disp( hk(i,1:hl(i))) ; 
    end

encode_bit=0;
for i=1:s(1,2)
    for j=1:length(sym)
        if(data(1,i)==symbol(j))
           encode_bit=[encode_bit,hk(j,1:hl(j))];
        end
    end
end

disp('按任意键察看整个数据编码（压缩）结果');
pause;
encode_bit

max=size(encode_bit);
h_tree=hufftree(hl,hk);  
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%解码（解压缩）%%%%%%%%%%%%%%%%%%%%
i=2;
j=1;
pos_0=2;
pos_1=3;

while(i<=max(1,2))
    if(encode_bit(1,i)==0)
        if(h_tree(pos_0,1)==0)
           temp1=h_tree(pos_0,2);
           temp2=h_tree(pos_0,3);
           pos_0=temp1;
           pos_1=temp2;
        else
           position(j)=h_tree(pos_0,2);
           pos_0=2;
           pos_1=3;
           j=j+1;
        end
     else
         if(h_tree(pos_1,1)==0)
           temp1=h_tree(pos_1,2); 
           temp2=h_tree(pos_1,3);
           pos_0=temp1; 
           pos_1=temp2;
         else
           position(j)=h_tree(pos_1,2);
           pos_0=2;
           pos_1=3;
           j=j+1;
         end
     end
  i=i+1;
end

position;
for i=1:j-1
data_decode(i)=symbol(position(1,i),1);
end

   disp('按任意键察看数据解码（解压缩）结果');
    pause; 
data_decode
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