comparison toolboxes/FullBNT-1.0.7/bnt/inference/static/@stab_cond_gauss_inf_engine/stab_cond_gauss_inf_engine.m @ 0:e9a9cd732c1e tip

first hg version after svn

+function engine = stab_cond_gauss_inf_engine(bnet)
+% STAB_COND_GAUSS_INF_ENGINE Junction tree using stable CG potentials
+% engine = cond_gauss_inf_engine(bnet)
+% 
+% This class was written by Shan Huang ([e-mail]) 2001
+% and fixed by Rainer Deventer [e-mail] March 2003
+N = length(bnet.dag);
+clusters = {};
+root = N;
+stages = { 1:N };
+onodes = [];
+engine = init_fields;
+engine.evidence = [];
+engine = class(engine, 'stab_cond_gauss_inf_engine', inf_engine(bnet));
+
+ns = bnet.node_sizes(:);
+ns(onodes) = 1; % observed nodes have only 1 possible value
+
+%[engine.jtree, dummy, engine.cliques, B, w, elim_order, moral_edges, fill_in_edges, strong] = ...
+%    dag_to_jtree(bnet, onodes, stages, clusters);
+
+
+partial_order = determine_elim_constraints(bnet, onodes);
+strong = ~isempty(partial_order);
+stages = {};
+clusters = {};
+[engine.jtree, dummy_root, engine.cliques, B, w, elim_order] = 
+    graph_to_jtree(moralize(bnet.dag), ns, partial_order, stages, clusters);
+
+    
+engine.cliques_bitv = B;
+engine.clique_weight = w;
+C = length(engine.cliques);
+engine.clpot = cell(1,C);
+
+% A node can be a member of many cliques, but is assigned to exactly one, to avoid
+% double-counting its CPD. We assign node i to clique c if c is the "lightest" clique that
+% contains i's family, so it can accomodate its CPD.
+
+engine.clq_ass_to_node = zeros(1, N);
+num_cliques = length(engine.cliques);
+for i=1:N
+  clqs_containing_family = find(all(B(:,family(bnet.dag, i)), 2)); % all selected columns must be 1
+  c = clqs_containing_family(argmin(w(clqs_containing_family)));  
+  engine.clq_ass_to_node(i) = c; 
+end
+
+% Compute the separators between connected cliques.
+[is,js] = find(engine.jtree > 0);
+engine.separator = cell(num_cliques, num_cliques);
+for k=1:length(is)
+  i = is(k); j = js(k);
+  engine.separator{i,j} = find(B(i,:) & B(j,:)); % intersect(cliques{i}, cliques{j});
+end
+%keyboard;
+engine.seppot = cell(C,C);
+
+pot_type = 'scg';
+check_for_cd_arcs([], bnet.cnodes, bnet.dag);
+
+% Make the jtree rooted, so there is a fixed message passing order.
+if strong
+  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+  % Start the search for the strong root at the clique with the  %
+  % highest number.                                              %
+  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+  root = length(engine.cliques);
+  root_found = 0;
+  
+  while ((~root_found) & (root >= 1))
+      root_found = test_strong_root(engine.jtree,engine.cliques,bnet.dnodes,root);
+      if ~root_found
+          root = root - 1;
+      end
+  end
+  assert(root > 0)
+  engine.root = root;
+  % the last clique is guaranteed to be a strong root
+  %engine.root = length(engine.cliques);
+else
+  % jtree_dbn_inf_engine requires the root to contain the interface.
+  % This may conflict with the strong root requirement! *********** BUG *************
+  engine.root = clq_containing_nodes(engine, root);
+  if engine.root <= 0
+    error(['no clique contains ' num2str(root)]);
+  end
+end  
+
+[engine.jtree, engine.preorder, engine.postorder] = mk_rooted_tree(engine.jtree, engine.root);
+
+% Evaluate CPDs with evidence, and convert to potentials  
+pot = cell(1, N);
+inited = zeros(1, C);
+clpot = cell(1, C);
+evidence = cell(1, N);
+for n=1:N
+  fam = family(bnet.dag, n);
+  e = bnet.equiv_class(n);
+  %pot{n} = CPD_to_scgpot(bnet.CPD{e}, fam, ns, bnet.cnodes, evidence);
+  pot{n} = convert_to_pot(bnet.CPD{e}, pot_type, fam(:), evidence);
+  cindex = engine.clq_ass_to_node(n);
+  if inited(cindex)
+      clpot{cindex} = direct_combine_pots(pot{n}, clpot{cindex});
+  else
+      clpot{cindex} = pot{n};
+      inited(cindex) = 1;
+  end
+end
+
+for i=1:C
+    if inited(i) == 0
+        clpot{i} = scgpot([], [], [], []);
+    end
+end
+
+seppot = cell(C, C);
+% separators are is not need to initialize
+
+% collect to root (node to parents)
+% Unlike the HUGIN architecture the complements are stored in the cliques during COLLECT 
+% and the separators are not playing a specific role during this process
+for n=engine.postorder(1:end-1)
+  for p=parents(engine.jtree, n)
+    if ~isempty(engine.separator{p,n})
+      %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+      % The empty case might happen for unlinked nodes, i.e. the DAG is not %
+      % a single tree, but a forest                                           %
+      %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+      [margpot, comppot] = complement_pot(clpot{n}, engine.separator{p,n});
+      clpot{n} = comppot;
+      clpot{p} = combine_pots(clpot{p}, margpot);
+    end
+  end
+end
+
+% distribute message from root
+% We have not to store the weak clique marginals and keep the original complement potentials. 
+% This is a minor variation of HUGIN architecture.
+temppot = clpot;
+for n=engine.preorder
+  for c=children(engine.jtree, n)
+    seppot{n,c} = marginalize_pot(temppot{n}, engine.separator{n,c});
+    temppot{c} = direct_combine_pots(temppot{c}, seppot{n,c});
+  end
+end
+
+engine.clpot = clpot;
+engine.seppot = seppot;
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+% init_fields()                  %
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+function engine = init_fields()
+
+engine.evidence = [];
+engine.jtree = [];
+engine.cliques = [];
+engine.cliques_bitv = [];
+engine.clique_weight = [];
+engine.preorder = [];
+engine.postorder = [];
+engine.root = []; 
+engine.clq_ass_to_node = [];
+engine.separator = [];
+engine.clpot =[];
+engine.seppot = [];
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