important.m

用matlab语言编的基于粗糙集理论的属性约简程序

function c=important(a,y,x)%求取正域

%a是条件属性，y是决策等价类，x是决策表
a
vind = insysind2(a,x);
%zzzzzzzzz=vind
%kk = vind
vtjlen = length(vind); 
vjclen = length(y);
% y
% y{1}
% y{2}
%存储下近似
for i=1:vjclen-1
    m{i}=[];
end
%求取下近似
for i=1:vjclen-1
    for j=1:vtjlen
%         vind{j}
%         y{i}
        zz=length(vind{j});
%         length(setdiff(vind{j},y{i}))
%         kk=(zz-length(setdiff(vind{j},y{i})))
        bian = (zz-length(setdiff(vind{j},y{i})))/zz;
      
        if bian>=0.6%0.6%0.7
            m{i}=cat(2,[m{i}],[j]);
        end
    end
end
c=m;