comparison toolboxes/FullBNT-1.0.7/graph/graph_to_jtree.m @ 0:e9a9cd732c1e tip

first hg version after svn

+function [jtree, root, cliques, B, w, elim_order] = graph_to_jtree(MG, ns, partial_order, stages, clusters)
+% GRAPH_TO_JTREE Triangulate a graph and make a junction tree from its cliques.
+% [jtree, root, cliques, B, w, elim_order] = ...
+%    graph_to_jtree(graph, node_sizes, partial_order, stages, clusters)
+%
+% INPUT:
+% graph(i,j) = 1 iff there is an edge between i,j
+% node_weights(i) = num discrete values node i can take on [1 if observed]
+% partial_order = {} if no constraints on elimination ordering
+% stages{i} = nodes that must be eliminated at i'th stage (if porder is empty)
+% clusters{i} = list of nodes that must get connected together in the moral graph
+%
+% OUTPUT:
+% jtree(i,j) = 1 iff there is an arc between clique i and clique j 
+% root = the root clique
+% cliques{i} = the nodes in clique i
+% B(i,j) = 1 iff node j occurs in clique i
+% w(i) = weight of clique i
+
+N = length(MG);
+
+if nargin >= 5
+  % Add extra arcs between nodes in each cluster to ensure they occur in the same clique
+  for i=1:length(clusters)
+    c = clusters{i};
+    MG(c,c) = 1;
+  end
+end
+MG = setdiag(MG, 0);
+
+% Find an optimal elimination ordering (NP-hard problem!)
+if nargin < 4
+  stages = {1:N};
+end
+if nargin < 3
+  partial_order = {};
+end
+if isempty(partial_order)
+  strong = 0;
+  elim_order = best_first_elim_order(MG, ns, stages);
+else
+  strong = 1;
+  elim_order = strong_elim_order(MG, ns, partial_order);
+end
+
+[MTG, cliques, fill_in_edges]  = triangulate(MG, elim_order);
+
+% Connect the cliques up into a jtree,
+[jtree, root, B, w] = cliques_to_jtree(cliques, ns);
+
+if 0
+  disp('testing dag to jtree');
+  % Find the cliques containing each node, and check they form a connected subtree
+  clqs_con_node = cell(1,N);
+  for i=1:N
+    clqs_con_node{i} = find(B(:,i))';
+  end
+  check_jtree_property(clqs_con_node, jtree);
+end