Mercurial > hg > camir-aes2014
diff toolboxes/FullBNT-1.0.7/bnt/inference/static/@jtree_inf_engine/jtree_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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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/toolboxes/FullBNT-1.0.7/bnt/inference/static/@jtree_inf_engine/jtree_inf_engine.m Tue Feb 10 15:05:51 2015 +0000 @@ -0,0 +1,141 @@ +function engine = jtree_inf_engine(bnet, varargin) +% JTREE_INF_ENGINE Junction tree inference engine +% engine = jtree_inf_engine(bnet, ...) +% +% The following optional arguments can be specified in the form of name/value pairs: +% [default value in brackets] +% +% clusters - a cell array of sets of nodes we want to ensure are in the same clique (in addition to families) [ {} ] +% root - the root of the junction tree will be a clique that contains this set of nodes [N] +% stages - stages{t} is a set of nodes we want to eliminate before stages{t+1}, ... [ {1:N} ] +% +% e.g., engine = jtree_inf_engine(bnet, 'maximize', 1); +% +% For more details on the junction tree algorithm, see +% - "Probabilistic networks and expert systems", Cowell, Dawid, Lauritzen and Spiegelhalter, Springer, 1999 +% - "Inference in Belief Networks: A procedural guide", C. Huang and A. Darwiche, +% Intl. J. Approximate Reasoning, 15(3):225-263, 1996. + + +% set default params +N = length(bnet.dag); +clusters = {}; +root = N; +stages = { 1:N }; +maximize = 0; + +if nargin >= 2 + args = varargin; + nargs = length(args); + if ~isstr(args{1}) + error('the interface to jtree has changed; now, onodes is not allowed and all optional params must be passed by name') + end + for i=1:2:nargs + switch args{i}, + case 'clusters', clusters = args{i+1}; + case 'root', root = args{i+1}; + case 'stages', stages = args{i+1}; + case 'maximize', maximize = args{i+1}; + otherwise, + error(['invalid argument name ' args{i}]); + end + end +end + +engine = init_fields; +engine = class(engine, 'jtree_inf_engine', inf_engine(bnet)); + +engine.maximize = maximize; + +onodes = bnet.observed; + +%[engine.jtree, dummy, engine.cliques, B, w, elim_order, moral_edges, fill_in_edges, strong] = ... +% dag_to_jtree(bnet, onodes, stages, clusters); + +porder = determine_elim_constraints(bnet, onodes); +strong = ~isempty(porder); +ns = bnet.node_sizes(:); +ns(onodes) = 1; % observed nodes have only 1 possible value +[engine.jtree, root2, engine.cliques, B, w] = ... + graph_to_jtree(moralize(bnet.dag), ns, porder, stages, clusters); + + +engine.cliques_bitv = B; +engine.clique_weight = w; +C = length(engine.cliques); +engine.clpot = cell(1,C); + +% Compute the separators between connected cliques. +[is,js] = find(engine.jtree > 0); +engine.separator = cell(C,C); +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 + +% 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); +for i=1:N + %c = clq_containing_nodes(engine, family(bnet.dag, i)); + 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 + +% Make the jtree rooted, so there is a fixed message passing order. +if strong + % the last clique is guaranteed to be a strong root + % engine.root_clq = length(engine.cliques); + + % --- 4/17/2010, by Wei Sun (George Mason University): + % It has been proved that the last clique is not necessary to be the + % strong root, instead, a clique called interface clique, that contains + % all discrete parents and at least one continuous node from a connected + % continuous component in a CLG, is guaranteed to be a strong root. + engine.root_clq = findroot(bnet, 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 = clq_containing_nodes(engine, root); + if engine.root_clq <= 0 + error(['no clique contains ' num2str(root)]); + end +end + +[engine.jtree, engine.preorder, engine.postorder] = mk_rooted_tree(engine.jtree, engine.root_clq); + +% collect +engine.postorder_parents = cell(1,length(engine.postorder)); +for n=engine.postorder(:)' + engine.postorder_parents{n} = parents(engine.jtree, n); +end +% distribute +engine.preorder_children = cell(1,length(engine.preorder)); +for n=engine.preorder(:)' + engine.preorder_children{n} = children(engine.jtree, n); +end + + + +%%%%%%%% + +function engine = init_fields() + +engine.jtree = []; +engine.cliques = []; +engine.separator = []; +engine.cliques_bitv = []; +engine.clique_weight = []; +engine.clpot = []; +engine.clq_ass_to_node = []; +engine.root_clq = []; +engine.preorder = []; +engine.postorder = []; +engine.preorder_children = []; +engine.postorder_parents = []; +engine.maximize = []; +engine.evidence = []; +