Added some more stuff to the sparse vector functions.

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%402955

dlib/svm/sparse_vector.h

@@ -68,6 +68,61 @@ namespace dlib
             return sum;
         }
 
+    // ------------------------------------------------------------------------------------
+
+        template <typename T, typename U, typename V, typename W>
+        typename T::value_type::second_type distance_squared (
+            const V& a_scale,
+            const T& a,
+            const W& b_scale,
+            const U& b
+        )
+        {
+            typedef typename T::value_type::second_type scalar_type;
+            typedef typename U::value_type::second_type scalar_typeU;
+            // Both T and U must contain the same kinds of elements
+            COMPILE_TIME_ASSERT((is_same_type<scalar_type, scalar_typeU>::value));
+
+            typename T::const_iterator ai = a.begin();
+            typename U::const_iterator bi = b.begin();
+
+            scalar_type sum = 0, temp = 0;
+            while (ai != a.end() && bi != b.end())
+            {
+                if (ai->first == bi->first)
+                {
+                    temp = a_scale*ai->second - b_scale*bi->second;
+                    ++ai;
+                    ++bi;
+                }
+                else if (ai->first < bi->first)
+                {
+                    temp = a_scale*ai->second;
+                    ++ai;
+                }
+                else 
+                {
+                    temp = b_scale*bi->second;
+                    ++bi;
+                }
+
+                sum += temp*temp;
+            }
+
+            while (ai != a.end())
+            {
+                sum += a_scale*a_scale*ai->second*ai->second;
+                ++ai;
+            }
+            while (bi != b.end())
+            {
+                sum += b_scale*b_scale*bi->second*bi->second;
+                ++bi;
+            }
+
+            return sum;
+        }
+
     // ------------------------------------------------------------------------------------
 
         template <typename T, typename U>
@@ -79,6 +134,19 @@ namespace dlib
             return std::sqrt(distance_squared(a,b));
         }
 
+    // ------------------------------------------------------------------------------------
+
+        template <typename T, typename U, typename V, typename W>
+        typename T::value_type::second_type distance (
+            const V& a_scale,
+            const T& a,
+            const W& b_scale,
+            const U& b
+        )
+        {
+            return std::sqrt(distance_squared(a_scale,a,b_scale,b));
+        }
+
     // ------------------------------------------------------------------------------------
 
         template <typename T, typename U>
@@ -148,6 +216,20 @@ namespace dlib
             return std::sqrt(length_squared(a));
         }
 
+    // ------------------------------------------------------------------------------------
+
+        template <typename T, typename U>
+        typename T::value_type::second_type scale_by (
+            T& a,
+            const U& value
+        )
+        {
+            for (typename T::iterator i = a.begin(); i != a.end(); ++i)
+            {
+                i->second *= value;
+            }
+        }
+
     }
 
 // ----------------------------------------------------------------------------------------

dlib/svm/sparse_vector_abstract.h

@@ -47,6 +47,24 @@ namespace dlib
                   a and b
         !*/
 
+    // ----------------------------------------------------------------------------------------
+
+        template <typename T, typename U, typename V, typename W>
+        typename T::value_type::second_type distance_squared (
+            const V& a_scale,
+            const T& a,
+            const W& b_scale,
+            const U& b
+        );
+        /*!
+            requires
+                - a is a sorted range of std::pair objects
+                - b is a sorted range of std::pair objects
+            ensures
+                - returns the squared distance between the vectors
+                  a_scale*a and b_scale*b
+        !*/
+
     // ----------------------------------------------------------------------------------------
 
         template <typename T, typename U>
@@ -63,6 +81,24 @@ namespace dlib
                   a and b.  (i.e. std::sqrt(distance_squared(a,b)))
         !*/
 
+    // ----------------------------------------------------------------------------------------
+
+        template <typename T, typename U, typename V, typename W>
+        typename T::value_type::second_type distance (
+            const V& a_scale,
+            const T& a,
+            const W& b_scale,
+            const U& b
+        );
+        /*!
+            requires
+                - a is a sorted range of std::pair objects
+                - b is a sorted range of std::pair objects
+            ensures
+                - returns the distance between the vectors
+                  a_scale*a and b_scale*b.  (i.e. std::sqrt(distance_squared(a_scale,a,b_scale,b)))
+        !*/
+
     // ----------------------------------------------------------------------------------------
 
         template <typename T, typename U>
@@ -106,6 +142,21 @@ namespace dlib
                 - returns std::sqrt(length_squared(a,a))
         !*/
 
+    // ----------------------------------------------------------------------------------------
+
+        template <typename T, typename U>
+        typename T::value_type::second_type scale_by (
+            T& a,
+            const U& value
+        );
+        /*!
+            requires
+                - a is a sorted range of std::pair objects
+            ensures
+                - #a == a*value
+                  (i.e. multiplies every element of the vector a by value)
+        !*/
+
     }
 
 // ----------------------------------------------------------------------------------------