?? prob_node.m
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function [P, p] = prob_node(CPD, self_ev, pev)
% PROB_NODE Compute prod_m P(x(i,m)| x(pi_i,m), theta_i) for node i (discrete)
% [P, p] = prob_node(CPD, self_ev, pev)
%
% self_ev(m) is the evidence on this node in case m.
% pev(i,m) is the evidence on the i'th parent in case m (if there are any parents).
% (These may also be cell arrays.)
%
% p(m) = P(x(i,m)| x(pi_i,m), theta_i)
% P = prod p(m)
if iscell(self_ev), usecell = 1; else usecell = 0; end
ncases = length(self_ev);
sz = dom_sizes(CPD);
nparents = length(sz)-1;
if nparents == 0
assert(isempty(pev));
else
assert(isequal(size(pev), [nparents ncases]));
end
n = length(sz);
dom = 1:n;
p = zeros(1, ncases);
if isa(CPD, 'tabular_CPD')
% speed up by looking up CPT using index Zhang Yimin 2001-12-31
if usecell
if nparents == 0
data = [cell2num(self_ev)];
else
data = [cell2num(pev); cell2num(self_ev)];
end
else
if nparents == 0
data = [self_ev];
else
data = [pev; self_ev];
end
end
indices = subv2ind(sz, data'); % each row of data' is a case
CPT=CPD_to_CPT(CPD);
p = CPT(indices);
%get the prob list
%cpt_size = prod(sz);
%prob_list=reshape(CPT, cpt_size, 1);
%for m=1:ncases %here we assume we get evidence for node and all its parents
% idx=indices(m);
% p(m)=prob_list(idx);
%end
else % eg. softmax
for m=1:ncases
if usecell
if nparents == 0
evidence = {self_ev{m}};
else
evidence = cell(1,n);
evidence(1:n-1) = pev(:,m);
evidence(n) = self_ev(m);
end
else
if nparents == 0
evidence = num2cell(self_ev(m));
else
evidence = num2cell([pev(:,m)', self_ev(m)]);
end
end
T = convert_to_table(CPD, dom, evidence);
p(m) = T;
end
end
P = prod(p);
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