From 2ce65f4cf8c4b026e7cc5508be766efc0d50033c Mon Sep 17 00:00:00 2001
From: Richard Roberts <richard.jw.roberts@gmail.com>
Date: Tue, 9 Jul 2013 17:50:45 +0000
Subject: [PATCH] VectorValuesUnordered::Zero

---
 gtsam/linear/VectorValuesUnordered.cpp | 9 +++++++++
 gtsam/linear/VectorValuesUnordered.h   | 3 +++
 2 files changed, 12 insertions(+)

diff --git a/gtsam/linear/VectorValuesUnordered.cpp b/gtsam/linear/VectorValuesUnordered.cpp
index dc252afca..9c2a3182b 100644
--- a/gtsam/linear/VectorValuesUnordered.cpp
+++ b/gtsam/linear/VectorValuesUnordered.cpp
@@ -55,6 +55,15 @@ namespace gtsam {
       throw std::invalid_argument("Requested to merge two VectorValues that have one or more variables in common.");
   }
 
+  /* ************************************************************************* */
+  VectorValuesUnordered VectorValuesUnordered::Zero(const VectorValuesUnordered& other)
+  {
+    VectorValuesUnordered result;
+    BOOST_FOREACH(const KeyValuePair& v, other)
+      result.values_.insert(make_pair(v.first, Vector::Zero(v.second.size())));
+    return result;
+  }
+
   /* ************************************************************************* */
   void VectorValuesUnordered::insert(const VectorValuesUnordered& values)
   {
diff --git a/gtsam/linear/VectorValuesUnordered.h b/gtsam/linear/VectorValuesUnordered.h
index 2db9c1898..0834a4d69 100644
--- a/gtsam/linear/VectorValuesUnordered.h
+++ b/gtsam/linear/VectorValuesUnordered.h
@@ -110,6 +110,9 @@ namespace gtsam {
     /** Merge two VectorValues into one, this is more efficient than inserting elements one by one. */
     VectorValuesUnordered(const VectorValuesUnordered& first, const VectorValuesUnordered& second);
 
+    /** Create a VectorValues with the same structure as \c other, but filled with zeros. */
+    static VectorValuesUnordered Zero(const VectorValuesUnordered& other);
+
     /// @}
     /// @name Standard Interface
     /// @{