huffman.m

matlab编写

function [h,l]=huffman(p);      %求哈夫曼编码h：按概率大小排列，及其平均码长l
if length(find(p<0))~=0        %判断输入是否概率分布   
    error('Input is not a prob.vector,there is negative component');   
end
if abs(sum(p)-1)>10e-10
    erroe('Input is not a prob.vector,the sum of the components is not equal to 1.');
end
n=length(p);      %得到输入的元素个数
q=p;
m=zeros(n-1,n);
for i=1:n-1
    [q,l]=sort(q);  %将输入的概率元素排序
    m(i,:)=[l(1:n-i+1),zeros(1,i-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,i: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);
    ll(i)=length(find(abs(h(i,:))~=32));
end
l=sum(p.*ll);