added erase method

cpp/GaussianFactor.h

@@ -118,6 +118,9 @@ public:
 		return As_.at(key);
 	}
 
+	/** erase the A associated with the input key */
+	size_t erase_A(const Symbol& key) { return As_.erase(key); }
+
 	/** operator[] syntax for get */
 	inline const Matrix& operator[](const Symbol& name) const {
 		return get_A(name);

cpp/testGaussianFactor.cpp

@@ -803,6 +803,24 @@ TEST ( GaussianFactor, exploding_MAST_factor ) {
 	CHECK(true);
 }
 
+/* ************************************************************************* */
+TEST( GaussianFactor, erase)
+{
+	Vector b = Vector_(3, 1., 2., 3.);
+	SharedDiagonal noise = noiseModel::Diagonal::Sigmas(Vector_(3,1.,1.,1.));
+	Symbol x0('x',0), x1('x',1);
+	std::list<std::pair<Symbol, Matrix> > terms;
+	terms.push_back(make_pair(x0, eye(2)));
+	terms.push_back(make_pair(x1, 2.*eye(2)));
+
+	GaussianFactor actual(terms, b, noise);
+	int erased = actual.erase_A(x0);
+
+	LONGS_EQUAL(1, erased);
+	GaussianFactor expected(x1, 2.*eye(2), b, noise);
+	CHECK(assert_equal(expected, actual));
+}
+
 
 /* ************************************************************************* */
 int main() { TestResult tr; return TestRegistry::runAllTests(tr);}