wehub-resource-sync
62 lines
1.6 KiB
Matlab
Executable File
62 lines
1.6 KiB
Matlab
Executable File
function [nodeBel, edgeBel] = mrfBelProp(A, nodePot, edgePot, epoch)
|
|
% Belief propagation for MRF (Assuming that egdePot is symmetric)
|
|
% Input:
|
|
% A: n x n adjacent matrix of undirected graph, where value is edge index
|
|
% nodePot: k x n node potential
|
|
% edgePot: k x k x m edge potential
|
|
% Output:
|
|
% nodeBel: k x n node belief
|
|
% edgeBel: k x k x m edge belief
|
|
% Written by Mo Chen (sth4nth@gmail.com)
|
|
tol = 0;
|
|
if nargin < 4
|
|
epoch = 50;
|
|
tol = 1e-8;
|
|
end
|
|
|
|
nodePot = exp(-nodePot);
|
|
edgePot = exp(-edgePot);
|
|
|
|
[k,n] = size(nodePot);
|
|
m = size(edgePot,3);
|
|
|
|
[s,t,e] = find(tril(A));
|
|
A = sparse([s;t],[t;s],[e;e+m]); % digraph adjacent matrix, where value is message index
|
|
mu = ones(k,2*m)/k; % message
|
|
for iter = 1:epoch
|
|
mu0 = mu;
|
|
for i = 1:n
|
|
in = nonzeros(A(:,i)); % incoming message index
|
|
nb = nodePot(:,i).*prod(mu(:,in),2); % product of incoming message
|
|
for l = in'
|
|
ep = edgePot(:,:,ud(l,m));
|
|
mu(:,rd(l,m)) = normalize(ep*(nb./mu(:,l)));
|
|
end
|
|
end
|
|
if max(abs(mu(:)-mu0(:))) < tol; break; end
|
|
end
|
|
|
|
nodeBel = zeros(k,n);
|
|
for i = 1:n
|
|
nodeBel(:,i) = nodePot(:,i).*prod(mu(:,nonzeros(A(:,i))),2);
|
|
end
|
|
nodeBel = normalize(nodeBel,1);
|
|
|
|
edgeBel = zeros(k,k,m);
|
|
for l = 1:m
|
|
eij = e(l);
|
|
eji = eij+m;
|
|
ep = edgePot(:,:,eij);
|
|
nbt = nodeBel(:,t(l))./mu(:,eij);
|
|
nbs = nodeBel(:,s(l))./mu(:,eji);
|
|
eb = (nbt*nbs').*ep;
|
|
edgeBel(:,:,eij) = eb./sum(eb(:));
|
|
end
|
|
|
|
function i = rd(i, m)
|
|
% reverse direction edge index
|
|
i = mod(i+m-1,2*m)+1;
|
|
|
|
function i = ud(i, m)
|
|
% undirected edge index
|
|
i = mod(i-1,m)+1; |