comparison toolboxes/FullBNT-1.0.7/bnt/general/mk_named_CPT.m @ 0:e9a9cd732c1e tip

first hg version after svn

+function CPT2 = mk_named_CPT(family_names, names, dag, CPT1)
+% MK_NAMED_CPT Permute the dimensions of a CPT so they agree with the internal numbering convention
+% CPT2 = mk_named_CPT(family_names, names, dag, CPT1)
+%
+% This is best explained by example.
+% Consider the following directed acyclic graph
+%
+%     C
+%   /   \
+%  R     S
+%   \   /
+%     W
+%
+% where all arcs point down.
+% When we create the CPT for node W, we consider S as its first parent, and R as its
+% second, and hence write
+%
+%      S R W
+% CPT1(1,1,:) = [1.0 0.0];
+% CPT1(2,1,:) = [0.2 0.8];  % P(W=1 | R=1, S=2) = 0.2
+% CPT1(1,2,:) = [0.1 0.9]; 
+% CPT1(2,2,:) = [0.01 0.99];
+%
+% However, when we create the dag using mk_adj_mat, the nodes get topologically sorted,
+% and by chance, node R preceeds node S in this ordering.
+% Hence we should have written
+%
+%      R S W
+% CPT2(1,1,:) = [1.0 0.0];
+% CPT2(2,1,:) = [0.1 0.9];
+% CPT2(1,2,:) = [0.2 0.8]; % P(W=1 | R=1, S=2) = 0.2
+% CPT2(2,2,:) = [0.01 0.99];
+%
+% Since we do not know the order of the nodes in advance, we can write
+%   CPT2 = mk_named_CPT({'S', 'R', 'W'}, names, dag, CPT1)
+% where 'S', 'R', 'W' are the order of the dimensions we assumed (the child node must be last in this list),
+% and names{i} is the name of the i'th node.
+
+n = length(family_names);
+family_nums = zeros(1,n);
+for i=1:n
+  family_nums(i) = stringmatch(family_names{i}, names); % was strmatch
+end
+
+fam = family(dag, family_nums(end));
+perm = zeros(1,n);
+for i=1:n
+  %  perm(i) = find(family_nums(i) == fam);
+  perm(i) = find(fam(i) == family_nums);
+end
+
+CPT2 = permute(CPT1, perm);