Added a probabilistic trainer adapter.

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%404075

dlib/svm/svm.h

@@ -646,6 +646,48 @@ namespace dlib
         return probabilistic_function<typename trainer_type::trained_function_type>( A, B, trainer.train(x,y) );
     }
 
+// ----------------------------------------------------------------------------------------
+
+    template <typename trainer_type>
+    struct trainer_adapter_probabilistic
+    {
+        typedef probabilistic_function<typename trainer_type::trained_function_type> trained_function_type;
+
+        const trainer_type& trainer;
+        const long folds;
+
+        trainer_adapter_probabilistic (
+            const trainer_type& trainer_,
+            const long folds_
+        ) : trainer(trainer_),folds(folds_) {}
+
+        template <
+            typename sample_type, 
+            typename scalar_type,
+            typename alloc_type1,
+            typename alloc_type2
+            >
+        const trained_function_type train (
+            const std::vector<sample_type,alloc_type1>& samples,
+            const std::vector<scalar_type,alloc_type2>& labels
+        ) const
+        {
+            return train_probabilistic_decision_function(trainer, samples, labels, folds);
+        }
+
+    };
+
+    template <
+        typename trainer_type
+        >
+    trainer_adapter_probabilistic<trainer_type> probabilistic (
+        const trainer_type& trainer,
+        const long folds
+    )
+    {
+        return trainer_adapter_probabilistic<trainer_type>(trainer,folds); 
+    }
+
 // ----------------------------------------------------------------------------------------
 // ----------------------------------------------------------------------------------------
 

dlib/svm/svm_abstract.h

@@ -96,6 +96,24 @@ namespace dlib
             - std::bad_alloc
     !*/
 
+// ----------------------------------------------------------------------------------------
+
+    template <
+        typename trainer_type
+        >
+    trainer_adapter_probabilistic<trainer_type> probabilistic (
+        const trainer_type& trainer,
+        const long folds
+    );
+    /*!
+        requires
+            - 1 < folds <= x.size()
+            - trainer_type == some kind of batch trainer object (e.g. svm_nu_trainer)
+        ensures
+            - returns a trainer adapter TA such that calling TA.train(samples, labels)
+              returns the same object as calling train_probabilistic_decision_function(trainer,samples,labels,folds).
+    !*/
+
 // ----------------------------------------------------------------------------------------
 // ----------------------------------------------------------------------------------------
 //                                  Miscellaneous functions