From 0a842cf0ec1cd5d1b306ef95cbd464b9e78233b2 Mon Sep 17 00:00:00 2001
From: Alex Cunningham <alexgcunningham@gmail.com>
Date: Thu, 2 Feb 2012 22:45:41 +0000
Subject: [PATCH] Added empty() to graphs

---
 gtsam/inference/FactorGraph.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/gtsam/inference/FactorGraph.h b/gtsam/inference/FactorGraph.h
index 458588b7b..12855e0c0 100644
--- a/gtsam/inference/FactorGraph.h
+++ b/gtsam/inference/FactorGraph.h
@@ -138,6 +138,9 @@ template<class CONDITIONAL, class CLIQUE> class BayesTree;
 		/** return the number of factors and NULLS */
 		size_t size() const { return factors_.size();}
 
+		/** Simple check for an empty graph - faster than comparing size() to zero */
+		bool empty() const { return factors_.empty(); }
+
 		/** const cast to the underlying vector of factors */
 		operator const std::vector<sharedFactor>&() const { return factors_; }