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1 function [P, p] = prob_node(CPD, self_ev, pev)
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2 % PROB_NODE Compute prod_m P(x(i,m)| x(pi_i,m), theta_i) for node i (discrete)
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3 % [P, p] = prob_node(CPD, self_ev, pev)
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4 %
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5 % self_ev(m) is the evidence on this node in case m.
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6 % pev(i,m) is the evidence on the i'th parent in case m (if there are any parents).
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7 % (These may also be cell arrays.)
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8 %
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9 % p(m) = P(x(i,m)| x(pi_i,m), theta_i)
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10 % P = prod p(m)
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11
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12 if iscell(self_ev), usecell = 1; else usecell = 0; end
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13
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14 ncases = length(self_ev);
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15 sz = dom_sizes(CPD);
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16
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17 nparents = length(sz)-1;
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18 if nparents == 0
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19 assert(isempty(pev));
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20 else
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21 assert(isequal(size(pev), [nparents ncases]));
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22 end
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23
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24 n = length(sz);
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25 dom = 1:n;
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26 p = zeros(1, ncases);
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27 if isa(CPD, 'tabular_CPD')
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28 % speed up by looking up CPT using index Zhang Yimin 2001-12-31
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29 if usecell
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30 if nparents == 0
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31 data = [cell2num(self_ev)];
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32 else
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33 data = [cell2num(pev); cell2num(self_ev)];
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34 end
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35 else
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36 if nparents == 0
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37 data = [self_ev];
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38 else
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39 data = [pev; self_ev];
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40 end
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41 end
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42
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43 indices = subv2ind(sz, data'); % each row of data' is a case
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44
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45 CPT=CPD_to_CPT(CPD);
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46 p = CPT(indices);
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47
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48 %get the prob list
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49 %cpt_size = prod(sz);
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50 %prob_list=reshape(CPT, cpt_size, 1);
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51 %for m=1:ncases %here we assume we get evidence for node and all its parents
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52 % idx=indices(m);
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53 % p(m)=prob_list(idx);
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54 %end
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55
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56 else % eg. softmax
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57
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58 for m=1:ncases
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59 if usecell
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60 if nparents == 0
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61 evidence = {self_ev{m}};
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62 else
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63 evidence = cell(1,n);
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64 evidence(1:n-1) = pev(:,m);
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65 evidence(n) = self_ev(m);
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66 end
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67 else
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68 if nparents == 0
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69 evidence = num2cell(self_ev(m));
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70 else
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71 evidence = num2cell([pev(:,m)', self_ev(m)]);
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72 end
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73 end
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74 T = convert_to_table(CPD, dom, evidence);
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75 p(m) = T;
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76 end
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77 end
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78
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79 P = prod(p);
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80
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81
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