Minor Improvements

examples/UGM_chain.cpp

@@ -13,7 +13,7 @@
  * @file small.cpp
  * @brief UGM (undirected graphical model) examples: chain
  * @author Frank Dellaert
- * @author Abhijit
+ * @author Abhijit Kundu
  *
  * See http://www.di.ens.fr/~mschmidt/Software/UGM/chain.html
  * for more explanation. This code demos the same example using GTSAM.

examples/UGM_small.cpp

@@ -49,21 +49,17 @@ int main(int argc, char** argv) {
 
 	// Print the UGM distribution
 	cout << "\nUGM distribution:" << endl;
-	for (size_t a = 0; a < nrStates; a++)
-		for (size_t m = 0; m < nrStates; m++)
-			for (size_t h = 0; h < nrStates; h++)
-				for (size_t c = 0; c < nrStates; c++) {
-					DiscreteFactor::Values values;
-					values[1] = c;
-					values[2] = h;
-					values[3] = m;
-					values[4] = a;
-					double prodPot = graph(values);
-					cout << c << " " << h << " " << m << " " << a << " :\t"
-							<< prodPot << "\t" << prodPot/3790 << endl;
-				}
+	vector<DiscreteFactor::Values> allPosbValues = cartesianProduct(
+			Cathy & Heather & Mark & Allison);
+	for (size_t i = 0; i < allPosbValues.size(); ++i) {
+		DiscreteFactor::Values values = allPosbValues[i];
+		double prodPot = graph(values);
+		cout << values[Cathy.first] << " " << values[Heather.first] << " "
+				<< values[Mark.first] << " " << values[Allison.first] << " :\t"
+				<< prodPot << "\t" << prodPot / 3790 << endl;
+	}
 
-	// "Decoding", i.e., configuration with largest value
+	// "Decoding", i.e., configuration with largest value (MPE)
 	// We use sequential variable elimination
 	DiscreteSequentialSolver solver(graph);
 	DiscreteFactor::sharedValues optimalDecoding = solver.optimize();

gtsam/discrete/Assignment.h

@@ -20,8 +20,10 @@
 
 #include <boost/foreach.hpp>
 #include <iostream>
+#include <vector>
 #include <map>
 
+
 namespace gtsam {
 
 	/**
@@ -42,6 +44,44 @@ namespace gtsam {
 		bool equals(const Assignment& other, double tol = 1e-9) const {
 			return (*this == other);
 		}
-	}; //Assignment
+	};	//Assignment
+
+
+	/**
+	 * @brief Get Cartesian product consisting all possible configurations
+	 * @param vector list of keys (label,cardinality) pairs.
+	 * @return vector list of all possible value assignments
+	 *
+	 * This function returns a vector of Assignment values for all possible
+	 * (Cartesian product) configurations of set of Keys which are nothing
+	 * but (Label,cardinality) pairs. This function should NOT be called for
+	 * more than a small number of variables and cardinalities. E.g. For 6
+	 * variables with each having cardinalities 4, we get 4096 possible
+	 * configurations!!
+	 */
+	template<typename L>
+	std::vector<Assignment<L> > cartesianProduct(
+			const std::vector<std::pair<L, size_t> >& keys) {
+		std::vector<Assignment<L> > allPossValues;
+		Assignment<L> values;
+		typedef std::pair<L, size_t> DiscreteKey;
+		BOOST_FOREACH(const DiscreteKey& key, keys)
+			values[key.first] = 0;	//Initialize from 0
+		while (1) {
+			allPossValues.push_back(values);
+			size_t j = 0;
+			for (j = 0; j < keys.size(); j++) {
+				L idx = keys[j].first;
+				values[idx]++;
+				if (values[idx] < keys[j].second)
+					break;
+				//Wrap condition
+				values[idx] = 0;
+			}
+			if (j == keys.size())
+				break;
+		}
+		return allPossValues;
+	}
 
 } // namespace gtsam

gtsam/discrete/DecisionTreeFactor.h

@@ -127,9 +127,16 @@ namespace gtsam {
 		 */
 		shared_ptr combine(size_t nrFrontals, ADT::Binary op) const;
 
+		/**
+		 * @brief Permutes the keys in Potentials and DiscreteFactor
+		 *
+		 * This re-implements the permuteWithInverse() in both Potentials
+		 * and DiscreteFactor by doing both of them together.
+		 */
+
 		void permuteWithInverse(const Permutation& inversePermutation){
 			DiscreteFactor::permuteWithInverse(inversePermutation);
-			Potentials::permute(inversePermutation);
+			Potentials::permuteWithInverse(inversePermutation);
 		}
 
 		/// @}

gtsam/discrete/DiscreteConditional.cpp

@@ -75,41 +75,38 @@ namespace gtsam {
 
 	/* ******************************************************************************** */
 	void DiscreteConditional::solveInPlace(Values& values) const {
+//		OLD
 //		assert(nrFrontals() == 1);
 //		Index j = (firstFrontalKey());
 //		size_t mpe = solve(values); // Solve for variable
 //		values[j] = mpe; // store result in partial solution
+//		OLD
 
 		// TODO: is this really the fastest way? I think it is.
+
+		//The following is to make make adjustment for nFrontals \neq 1
 		ADT pFS = choose(values); // P(F|S=parentsValues)
 
 		// Initialize
 		Values mpe;
-		Values frontalVals;
-		BOOST_FOREACH(Index j, frontals()) {
-			frontalVals[j] = 0;
-		}
 		double maxP = 0;
 
-		while (1) {
+		DiscreteKeys keys;
+		BOOST_FOREACH(Index idx, frontals()) {
+			DiscreteKey dk(idx,cardinality(idx));
+			keys & dk;
+		}
+		// Get all Possible Configurations
+		vector<Values> allPosbValues = cartesianProduct(keys);
+
+		// Find the MPE
+		BOOST_FOREACH(Values& frontalVals, allPosbValues) {
 			double pValueS = pFS(frontalVals); // P(F=value|S=parentsValues)
 			// Update MPE solution if better
 			if (pValueS > maxP) {
 				maxP = pValueS;
 				mpe = frontalVals;
 			}
-
-			size_t j = 0;
-			for (j = 0; j < nrFrontals(); j++) {
-				Index idx = frontals()[j];
-				frontalVals[idx]++;
-				if (frontalVals[idx] < cardinality(idx))
-					break;
-				//Wrap condition
-				frontalVals[idx] = 0;
-			}
-			if (j == nrFrontals())
-				break;
 		}
 
 		//set values (inPlace) to mpe
@@ -197,7 +194,7 @@ namespace gtsam {
 	/* ******************************************************************************** */
 	void DiscreteConditional::permuteWithInverse(const Permutation& inversePermutation){
 		IndexConditional::permuteWithInverse(inversePermutation);
-		Potentials::permute(inversePermutation);
+		Potentials::permuteWithInverse(inversePermutation);
 	}
 
 

gtsam/discrete/Potentials.cpp

@@ -60,7 +60,7 @@ namespace gtsam {
 	}
 
 	/* ************************************************************************* */
-	void Potentials::permute(const Permutation& permutation) {
+	void Potentials::permuteWithInverse(const Permutation& permutation) {
 		// Permute the _cardinalities (TODO: Inefficient Consider Improving)
 		DiscreteKeys keys;
 		map<Index, Index> ordering;
@@ -72,7 +72,6 @@ namespace gtsam {
 		// Perform Permutation
 		BOOST_FOREACH(DiscreteKey& key, keys) {
 			ordering[key.first] = permutation[key.first];
-			//cout << key.first << " -> " << ordering[key.first] << endl;
 			key.first = ordering[key.first];
 		}
 

gtsam/discrete/Potentials.h

@@ -73,8 +73,10 @@ namespace gtsam {
 		 * @brief Permutes the keys in Potentials
 		 *
 		 * This permutes the Indices and performs necessary re-ordering of ADD.
+		 * This is virtual so that derived types e.g. DecisionTreeFactor can
+		 * re-implement it.
 		 */
-		void permute(const Permutation& perm);
+		virtual void permuteWithInverse(const Permutation& inversePermutation);
 
 	}; // Potentials
 

gtsam/discrete/tests/testDiscreteMarginals.cpp

@@ -10,8 +10,8 @@
  * -------------------------------------------------------------------------- */
 
 /*
- * @ file testDiscreteMarginals.cpp
- * @date Feb 14, 2011
+ * @file testDiscreteMarginals.cpp
+ * @date Jun 7, 2012
  * @author Abhijit Kundu
  * @author Richard Roberts
  * @author Frank Dellaert