Added overloads for dot() so you can dot() a std::vector with a std::map.

dlib/svm/sparse_vector.h

@@ -7,6 +7,8 @@
 #include <cmath>
 #include <limits>
 #include "../algs.h"
+#include <vector>
+#include <map>
 
 
 namespace dlib
@@ -216,16 +218,18 @@ namespace dlib
 
     // ------------------------------------------------------------------------------------
 
-        template <typename T>
+        namespace impl
+        {
+            template <typename T, typename U>
             typename T::value_type::second_type dot (
                 const T& a,
-            const T& b
+                const U& b
             )
             {
                 typedef typename T::value_type::second_type scalar_type;
 
                 typename T::const_iterator ai = a.begin();
-            typename T::const_iterator bi = b.begin();
+                typename U::const_iterator bi = b.begin();
 
                 scalar_type sum = 0;
                 while (ai != a.end() && bi != b.end())
@@ -248,6 +252,34 @@ namespace dlib
 
                 return sum;
             }
+        }
+
+        template <typename T>
+        inline typename T::value_type::second_type dot (
+            const T& a,
+            const T& b
+        )
+        {
+            return dlib::sparse_vector::impl::dot(a,b);
+        }
+
+        template <typename T1, typename T2, typename T3, typename T4, typename T5, typename T6>
+        inline T4 dot (
+            const std::vector<T1,T2>& a,
+            const std::map<T3,T4,T5,T6>& b
+        )
+        {
+            return dlib::sparse_vector::impl::dot(a,b);
+        }
+
+        template <typename T1, typename T2, typename T3, typename T4, typename T5, typename T6>
+        inline T4 dot (
+            const std::map<T3,T4,T5,T6>& a,
+            const std::vector<T1,T2>& b
+        )
+        {
+            return dlib::sparse_vector::impl::dot(a,b);
+        }
 
     // ------------------------------------------------------------------------------------
 

dlib/svm/sparse_vector_abstract.h

@@ -6,6 +6,8 @@
 #include <cmath>
 #include "../algs.h"
 #include "../serialize.h"
+#include <map>
+#include <vector>
 
 namespace dlib
 {
@@ -164,6 +166,30 @@ namespace dlib
                 - returns the dot product between the vectors a and b
         !*/
 
+        template <typename T1, typename T2, typename T3, typename T4, typename T5, typename T6>
+        T4 dot (
+            const std::vector<T1,T2>& a,
+            const std::map<T3,T4,T5,T6>& b
+        );
+        /*!
+            requires
+                - a and b are sparse vectors 
+            ensures
+                - returns the dot product between the vectors a and b
+        !*/
+
+        template <typename T1, typename T2, typename T3, typename T4, typename T5, typename T6>
+        T4 dot (
+            const std::map<T3,T4,T5,T6>& a,
+            const std::vector<T1,T2>& b
+        );
+        /*!
+            requires
+                - a and b are sparse vectors 
+            ensures
+                - returns the dot product between the vectors a and b
+        !*/
+
     // ----------------------------------------------------------------------------------------
 
         template <typename T, typename EXP>