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view 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
author | wolffd |
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date | Tue, 10 Feb 2015 15:05:51 +0000 |
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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 (shan.huang@intel.com) 2001 % and fixed by Rainer Deventer deventer@informatik.uni-erlangen.de 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 = [];