huffman.m

实现霍夫曼编码,初学的好例子,新手入门,建议好好分析程序

%huffman编码
function [h,H,L]=huffman(p)
if length(find(p<0))~=0
    error('Not a prob.vector,negative component(s)')
end
if sum(p)>1
    error('Not a prob.vector,components do not add up to 1')
end 
H=-sum(p.*log2(p));
n=length(p);
q=p;
m=zeros(n-1,n);
for i=1:n-1
    [q,L]=sort(q);
    m(i,:)=[L(1:n-i+1),zeros(1,i-1)];
    q=[q(1)+q(2),q(3:n),1];
end
for i=1:n-1
    c(i,:)=blanks(n*n);
end
c(n-1,n)='0';
c(n-1,2*n)='1';
for i=2:n-1
    c(n-i,1:n-1)=c(n-i+1,n*(find(m(n-i+1,:)==1))...
    -(n-2):n*(find(m(n-i+1,:)==1)));
    c(n-i,n)='0';
    c(n-i,n+1:2*n-1)=c(n-i,1:n-1);
    c(n-i,2*n)='1';
    for j=1:i-1
        c(n-i,(j+1)*n+1:(j+2)*n)=c(n-i+1,...
        n*(find(m(n-i+1,:)==j+1)-1)+1:n*find(m(n-i+1,:)==j+1));
    end
end
for i=1:n
    h(i,1:n)=c(1,n*(find(m(1,:)==i)-1)+1:find(m(1,:)==i)*n);
    L1(i)=length(find(abs(h(i,:))~=32));
end
L=sum(p.*L1)