added saveGraph function to BayesTree which writes out a dot file which can be visualized using graphviz dot command

cpp/BayesTree-inl.h

@@ -10,12 +10,14 @@
 
 #include <boost/foreach.hpp>
 #include <boost/assign/std/list.hpp> // for operator +=
+#include <fstream>
 using namespace boost::assign;
 
 #include "Conditional.h"
 #include "BayesTree.h"
 #include "Ordering.h"
 #include "inference-inl.h"
+#include "Key.h"
 
 namespace gtsam {
 
@@ -86,6 +88,47 @@ namespace gtsam {
 		}
 	}
 
+	/* ************************************************************************* */
+	template<class Conditional>
+	void BayesTree<Conditional>::saveGraph(const std::string &s) const {
+		ofstream of(s.c_str());
+		of<< "digraph G{\n";
+		saveGraph(of, root_);
+		of<<"}";
+		of.close();
+	}
+
+	template<class Conditional>
+	void BayesTree<Conditional>::saveGraph(ostream &s,
+			BayesTree<Conditional>::sharedClique clique,
+			int parentnum, int num) const {
+		bool first = true;
+		std::stringstream out;
+		out << num;
+		string parent = out.str();
+		parent += "[label=\"";
+		BOOST_FOREACH(boost::shared_ptr<Conditional> c, clique->conditionals_) {
+			if(!first) parent += ","; first = false;
+			parent += (string(c->key())).c_str();
+		}
+		if( clique != root_){
+			parent += " : ";
+			s << parentnum << "->" << num << "\n";
+		}
+		first = true;
+		BOOST_FOREACH(const Symbol& sep, clique->separator_) {
+			if(!first) parent += ","; first = false;
+			parent += ((string)sep).c_str();
+		}
+		parent += "\"];\n";
+		s << parent;
+		parentnum = num;
+		BOOST_FOREACH(sharedClique c, clique->children_) {
+			saveGraph(s, c, parentnum, ++num);
+		}
+	}
+
+
 	template<class Conditional>
 	typename BayesTree<Conditional>::CliqueStats
 	BayesTree<Conditional>::CliqueData::getStats() const {

cpp/BayesTree.h

@@ -127,6 +127,13 @@ namespace gtsam {
 		/** print */
 		void print(const std::string& s = "") const;
 
+		/** saves the Tree to a text file in GraphViz format */
+		void saveGraph(const std::string& s) const;
+	private:
+		void saveGraph(std::ostream &s, sharedClique clique,
+				int parentnum = 0, int num = 0) const;
+	public:
+
 		/** check equality */
 		bool equals(const BayesTree<Conditional>& other, double tol = 1e-9) const;
 
@@ -170,6 +177,7 @@ namespace gtsam {
 			CliqueStats getStats() const;
 		};
 		CliqueData getCliqueData() const;
+
 	private:
 		void getCliqueData(CliqueData& stats, sharedClique clique) const;
 	public: