mstep.m

greedy em 混和模型训练算法

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%%%%%% The M-step of EM algorithm                           %%%%%
%%%%%%                                                      %%%%%
%%%%%% Kostas Blekas, 19 Dec. 2001                          %%%%%
%%%%%% please contact at [e-mail] in case of problems %%
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function [motif_pr,back_pr,p] = Mstep(z,alpha,new_seq,k,n,g,L,W,thesh,parbeta)

c_mot = zeros(L,W,g);
c10 = zeros(1,W);
c_back = zeros(1,L);
mpr = zeros(L,W,g);

for j=1:g
    p(j) = sum(z(:,j)) / n;
    if k(j)    % j: motif
        for l=1:W 
            for i=1:L
               c_mot(i,l,j) = sum(z(find(new_seq(:,l)==alpha(i)),j));
            end
            motif_pr(:,l,j) = ( c_mot(:,l,j) + parbeta') ./ ( sum((c_mot(:,l,j))) + sum(parbeta) );
        end
    else           % j: background
        for l=1:L
            for i=1:W
                c10(i) = sum(z(find(new_seq(:,i)==alpha(l)),j));
            end
            c_back(l)=sum(c10);
        end
        back_pr(:,j) = (c_back' + parbeta') ./ ( sum(c_back) + sum(parbeta) );
    end
end