Mauch MIREX 2010

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);