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

first hg version after svn

+function [A, names] = mk_adj_mat(connections, names, topological)
+% MK_ADJ_MAT Make a directed adjacency matrix from a list of connections between named nodes.
+%
+% A = mk_adj_mat(connections, name)
+% This is best explaine by an example:
+%   names = {'WetGrass', 'Sprinkler', 'Cloudy', 'Rain'}; 
+%   connections = {'Cloudy', 'Sprinkler'; 'Cloudy', 'Rain'; 'Sprinkler', 'WetGrass'; 'Rain', 'WetGrass'}; 
+% adds the arcs C -> S, C -> R, S -> W, R -> W. Node 1 is W, 2 is S, 3 is C, 4 is R.
+%
+% [A, names] = mk_adj_mat(connections, name, 1)
+% The last argument of 1 indicates that we should topologically sort the nodes (parents before children).
+% In the example, the numbering becomes: node 1 is C, 2 is R, 3 is S, 4 is W
+% and the return value of names gets permuted to {'Cloudy', 'Rain', 'Sprinkler', 'WetGrass'}.
+% Note that topological sorting the graph is only possible if it has no directed cycles.
+
+if nargin < 3, topological = 0; end
+  
+n=length(names);
+A=zeros(n);
+[nr nc] = size(connections);
+for r=1:nr
+  from = strmatch(connections{r,1}, names, 'exact');
+  assert(~isempty(from));
+  to = strmatch(connections{r,2}, names, 'exact');
+  assert(~isempty(to));
+  %fprintf(1, 'from %s %d to %s %d\n', connections{r,1}, from, connections{r,2}, to);
+  A(from,to) = 1;
+end
+
+if topological
+  order = topological_sort(A); 
+  A = A(order, order); 
+  names = names(order); 
+end
+
+