- Added the ability to get the kernel and inverse kernel matrices out of a

linearly_independent_subset_finder.   I also made the add() function return
   a bool that tells you if it added its argument into the dictionary set
   or not.
 - Added a version of empirical_kernel_map::load() that accepts
   linearly_independent_subset_finder objects.

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%403615

dlib/svm/empirical_kernel_map.h

@@ -5,6 +5,7 @@
 
 #include "../matrix.h"
 #include "empirical_kernel_map_abstract.h"
+#include "linearly_independent_subset_finder.h"
 #include <vector>
 #include "../algs.h"
 #include "kernel_matrix.h"
@@ -71,6 +72,25 @@ namespace dlib
             load_impl(kernel_, vector_to_matrix(basis_samples));
         }
 
+        void load(
+            const linearly_independent_subset_finder<kernel_type>& lisf
+        )
+        {
+            // make sure requires clause is not broken
+            DLIB_ASSERT(lisf.dictionary_size() > 0,
+                "\tvoid empirical_kernel_map::load(linearly_independent_subset_finder)"
+                << "\n\t You have to give a non-empty set of basis_samples"
+                << "\n\t this: " << this
+                );
+
+            kernel = lisf.get_kernel();
+            weights = trans(chol(lisf.get_inv_kernel_marix()));
+            basis.resize(lisf.dictionary_size());
+            for (unsigned long i = 0; i < basis.size(); ++i)
+                basis[i] = lisf[i];
+
+        }
+
         const kernel_type get_kernel (
         ) const
         {

dlib/svm/empirical_kernel_map_abstract.h

@@ -7,6 +7,7 @@
 #include "../matrix.h"
 #include "kernel_abstract.h"
 #include "function_abstract.h"
+#include "linearly_independent_subset_finder_abstract.h"
 #include <vector>
 
 namespace dlib
@@ -142,6 +143,27 @@ namespace dlib
                     If this happens then this object will revert back to its initial value.
         !*/
 
+        void load(
+            const linearly_independent_subset_finder<kernel_type>& lisf
+        );
+        /*!
+            requires
+                - lisf.dictionary_size() > 0
+            ensures
+                - #out_vector_size() == lisf.dictionary_size() 
+                - #get_kernel() == lisf.get_kernel()
+                - Uses the dictionary vectors from lisf as a basis set.  Thus, this function 
+                  constructs a map between normal sample_type objects and the subspace of 
+                  the kernel feature space defined by the given kernel and the given set 
+                  of basis samples.  So after this function has been called you will be 
+                  able to project sample_type objects into kernel feature space and obtain 
+                  the resulting vector as a regular column matrix.
+            throws
+                - empirical_kernel_map_error
+                    This exception is thrown if we are unable to create a kernel map.
+                    If this happens then this object will revert back to its initial value.
+        !*/
+
         const kernel_type get_kernel (
         ) const;
         /*!

dlib/svm/linearly_independent_subset_finder.h

@@ -108,7 +108,7 @@ namespace dlib
             K.set_size(0,0);
         }
 
-        void add (
+        bool add (
             const sample_type& x
         )
         {
@@ -126,7 +126,9 @@ namespace dlib
                     K(0,0) = kx;
 
                     dictionary.push_back(x);
+                    return true;
                 }
+                return false;
             }
             else
             {
@@ -220,6 +222,11 @@ namespace dlib
                         dictionary.push_back(x);
 
                     }
+                    return true;
+                }
+                else
+                {
+                    return false;
                 }
             }
         }
@@ -285,6 +292,18 @@ namespace dlib
             return dictionary[index];
         }
 
+        const matrix<scalar_type,0,0,mem_manager_type>& get_kernel_matrix (
+        ) const
+        {
+            return K;
+        }
+
+        const matrix<scalar_type,0,0,mem_manager_type>& get_inv_kernel_marix (
+        ) const
+        {
+            return K_inv;
+        }
+
     private:
 
         typedef std_allocator<sample_type, mem_manager_type> alloc_sample_type;

dlib/svm/linearly_independent_subset_finder_abstract.h

@@ -112,19 +112,22 @@ namespace dlib
                 - clears out all the data (e.g. #dictionary_size() == 0)
         !*/
 
-        void add (
+        bool add (
             const sample_type& x
         );
         /*!
             ensures
                 - if (x is linearly independent of the vectors already in this object) then
                     - adds x into the dictionary
+                    - returns true
                     - if (dictionary_size() < max_dictionary_size()) then
                         - #dictionary_size() == dictionary_size() + 1
                     - else
                         - #dictionary_size() == dictionary_size() 
                           (i.e. the number of vectors in this object doesn't change)
                         - the least linearly independent vector in this object is removed
+                - else
+                    - returns false
         !*/
 
         void swap (
@@ -161,6 +164,25 @@ namespace dlib
                   vectors in this object.
         !*/
 
+        const matrix<scalar_type,0,0,mem_manager_type>& get_kernel_matrix (
+        ) const;
+        /*!
+            ensures
+                - returns a matrix K such that:
+                    - K.nr() == K.nc() == dictionary_size()
+                    - K == kernel_matrix(get_kernel(), get_dictionary())
+                      i.e. K == the kernel matrix for the dictionary vectors
+        !*/
+
+        const matrix<scalar_type,0,0,mem_manager_type>& get_inv_kernel_marix (
+        ) const;
+        /*!
+            ensures
+                - if (dictionary_size() != 0)
+                    - returns inv(get_kernel_matrix())
+                - else
+                    - returns an empty matrix
+        !*/
     };
 
 // ----------------------------------------------------------------------------------------