comparison toolboxes/FullBNT-1.0.7/bnt/CPDs/@discrete_CPD/prob_node.m @ 0:e9a9cd732c1e tip

first hg version after svn

+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);
+
+