add nrKeys and set

cpp/DSF.h

@@ -105,6 +105,14 @@ namespace gtsam {
 			return partitions;
 		}
 
+		// get the nodes in the given tree
+		Set set(const Label& label) {
+			Set set;
+			BOOST_FOREACH(const KeyLabel& pair, (Tree)*this)
+				if (pair.second==label) set.insert(pair.first);
+			return set;
+		}
+
 		/** equality */
 		bool operator==(const Self& t) const { return (Tree)*this == (Tree)t;	}
 

cpp/FactorGraph-inl.h

@@ -407,8 +407,7 @@ std::pair<FactorGraph<Factor>, FactorGraph<Factor> > FactorGraph<Factor>::splitM
 	DSF<Symbol> dsf(keys());
 
 	//	while G is nonempty and T is not yet spanning
-	size_t m = nrFactors();
-	for (size_t i=0;i<m;i++) {
+	for (size_t i=0;i<size();i++) {
 		const sharedFactor& f = factors_[i];
 
 		// retrieve the labels of all the keys

cpp/FactorGraph.h

@@ -92,6 +92,9 @@ namespace gtsam {
 		/** return keys in some random order */
 		Ordering keys() const;
 
+		/** return the number of the keys */
+		inline size_t nrKeys() const {return indices_.size(); };
+
 		/** Check whether a factor with this variable exists */
 		bool involves(const Symbol& key) const {
 			return !(indices_.find(key)==indices_.end());

cpp/testDSF.cpp

@@ -181,6 +181,20 @@ TEST(DSF, partition3) {
 	CHECK(expected == partitions[dsf.findSet(5)]);
 }
 
+/* ************************************************************************* */
+TEST(DSF, set) {
+	DSFInt dsf;
+	dsf = dsf.makeSet(5);
+	dsf = dsf.makeSet(6);
+	dsf = dsf.makeSet(7);
+	dsf = dsf.makeUnion(5,6);
+	set<int> set = dsf.set(5);
+	LONGS_EQUAL(2, set.size());
+
+	std::set<int> expected; expected += 5, 6;
+	CHECK(expected == set);
+}
+
 /* ************************************************************************* */
 int func(const int& a) { return a + 10; }
 TEST(DSF, map) {