Filled out spec and cleaned up code.

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%404197

dlib/svm/svm_multiclass_linear_trainer.h

@@ -8,6 +8,7 @@
 #include "../optimization/optimization_oca.h"
 #include "../matrix.h"
 #include "sparse_vector.h"
+#include "function.h"
 
 namespace dlib
 {
@@ -22,6 +23,12 @@ namespace dlib
     class multiclass_svm_problem : public structural_svm_problem<matrix_type,
                                                                  std::vector<std::pair<unsigned long,typename matrix_type::type> > > 
     {
+        /*!
+            WHAT THIS OBJECT REPRESENTS
+                This object defines the optimization problem for the multiclass SVM trainer
+                object at the bottom of this file.  
+        !*/
+
     public:
         typedef typename matrix_type::type scalar_type;
         typedef std::vector<std::pair<unsigned long,scalar_type> > feature_vector_type;
@@ -144,20 +151,124 @@ namespace dlib
         typedef multiclass_linear_decision_function<kernel_type, label_type> trained_function_type;
 
 
+        // You are getting a compiler error on this line because you supplied a non-linear kernel
+        // to the svm_c_linear_trainer object.  You have to use one of the linear kernels with this
+        // trainer.
+        COMPILE_TIME_ASSERT((is_same_type<K, linear_kernel<sample_type> >::value ||
+                             is_same_type<K, sparse_linear_kernel<sample_type> >::value ));
+
+        svm_multiclass_linear_trainer (
+        ) :
+            C(1),
+            eps(0.001),
+            verbose(false)
+        {
+        }
+
+        void set_epsilon (
+            scalar_type eps_
+        )
+        {
+            // make sure requires clause is not broken
+            DLIB_ASSERT(eps_ > 0,
+                "\t void svm_multiclass_linear_trainer::set_epsilon()"
+                << "\n\t eps_ must be greater than 0"
+                << "\n\t eps_: " << eps_ 
+                << "\n\t this: " << this
+                );
+
+            eps = eps_;
+        }
+
+        const scalar_type get_epsilon (
+        ) const { return eps; }
+
+        void be_verbose (
+        )
+        {
+            verbose = true;
+        }
+
+        void be_quiet (
+        )
+        {
+            verbose = false;
+        }
+
+        void set_oca (
+            const oca& item
+        )
+        {
+            solver = item;
+        }
+
+        const oca get_oca (
+        ) const
+        {
+            return solver;
+        }
+
+        const kernel_type get_kernel (
+        ) const
+        {
+            return kernel_type();
+        }
+
+        void set_c (
+            scalar_type C_
+        )
+        {
+            // make sure requires clause is not broken
+            DLIB_ASSERT(C_ > 0,
+                "\t void svm_multiclass_linear_trainer::set_c()"
+                << "\n\t C must be greater than 0"
+                << "\n\t C_:   " << C_ 
+                << "\n\t this: " << this
+                );
+
+            C = C_;
+        }
+
+        const scalar_type get_c (
+        ) const
+        {
+            return C;
+        }
+
         trained_function_type train (
             const std::vector<sample_type>& all_samples,
             const std::vector<label_type>& all_labels
         ) const
         {
-            oca solver;
+            scalar_type svm_objective = 0;
+            return train(all_samples, all_labels, svm_objective);
+        }
+
+        trained_function_type train (
+            const std::vector<sample_type>& all_samples,
+            const std::vector<label_type>& all_labels,
+            scalar_type& svm_objective
+        ) const
+        {
+            // make sure requires clause is not broken
+            DLIB_ASSERT(is_learning_problem(all_samples,all_labels),
+                "\t trained_function_type svm_multiclass_linear_trainer::train(all_samples,all_labels)"
+                << "\n\t invalid inputs were given to this function"
+                << "\n\t all_samples.size():     " << all_samples.size() 
+                << "\n\t all_labels.size():      " << all_labels.size() 
+                );
+
             typedef matrix<scalar_type,0,1> w_type;
             w_type weights;
             multiclass_svm_problem<w_type, sample_type, label_type> problem(all_samples, all_labels);
+            if (verbose)
                 problem.be_verbose();
+
             problem.set_max_cache_size(0);
-            problem.set_c(100);
+            problem.set_c(C);
+            problem.set_epsilon(eps);
 
-            solver(problem, weights);
+            svm_objective = solver(problem, weights);
 
             trained_function_type df;
 
@@ -167,6 +278,12 @@ namespace dlib
             df.b       = colm(reshape(weights, df.labels.size(), dims+1), dims);
             return df;
         }
+
+    private:
+        scalar_type C;
+        scalar_type eps;
+        bool verbose;
+        oca solver;
     };
 
 // ----------------------------------------------------------------------------------------

dlib/svm/svm_multiclass_linear_trainer_abstract.h

+// Copyright (C) 2011  Davis E. King (davis@dlib.net)
+// License: Boost Software License   See LICENSE.txt for the full license.
+#undef DLIB_SVm_MULTICLASS_LINEAR_TRAINER_ABSTRACT_H__ 
+#ifdef DLIB_SVm_MULTICLASS_LINEAR_TRAINER_ABSTRACT_H__
+
+#include "../matrix/matrix_abstract.h"
+#include "../algs.h"
+#include "function_abstract.h"
+#include "kernel_abstract.h"
+#include "sparse_kernel_abstract.h"
+#include "../optimization/optimization_oca_abstract.h"
+
+namespace dlib
+{
+
+// ----------------------------------------------------------------------------------------
+
+    template <
+        typename K,
+        typename label_type_ = typename K::scalar_type 
+        >
+    class svm_multiclass_linear_trainer
+    {
+        /*!
+            REQUIREMENTS ON K 
+                Is either linear_kernel or sparse_linear_kernel.  
+
+            REQUIREMENTS ON label_type_
+                label_type_ must be default constructable, copyable, and comparable using
+                operator < and ==.  It must also be possible to write it to an std::ostream
+                using operator<<.
+
+            INITIAL VALUE
+                - get_epsilon() == 0.001
+                - get_c() == 1
+                - this object will not be verbose unless be_verbose() is called
+                - #get_oca() == oca() (i.e. an instance of oca with default parameters) 
+
+            WHAT THIS OBJECT REPRESENTS
+                This object represents a tool for training a multiclass support 
+                vector machine.  It is optimized for the case where linear kernels 
+                are used.  
+        !*/
+
+    public:
+        typedef label_type_ label_type;
+        typedef K kernel_type;
+        typedef typename kernel_type::scalar_type scalar_type;
+        typedef typename kernel_type::sample_type sample_type;
+        typedef typename kernel_type::mem_manager_type mem_manager_type;
+        typedef multiclass_linear_decision_function<kernel_type, label_type> trained_function_type;
+
+        svm_multiclass_linear_trainer (
+        );
+        /*!
+            ensures
+                - this object is properly initialized
+        !*/
+
+        void set_epsilon (
+            scalar_type eps
+        );
+        /*!
+            requires
+                - eps > 0
+            ensures
+                - #get_epsilon() == eps 
+        !*/
+
+        const scalar_type get_epsilon (
+        ) const;
+        /*!
+            ensures
+                - returns the error epsilon that determines when training should stop.
+                  Smaller values may result in a more accurate solution but take longer 
+                  to execute.
+        !*/
+
+        void be_verbose (
+        );
+        /*!
+            ensures
+                - This object will print status messages to standard out so that a 
+                  user can observe the progress of the algorithm.
+        !*/
+
+        void be_quiet (
+        );
+        /*!
+            ensures
+                - this object will not print anything to standard out
+        !*/
+
+        void set_oca (
+            const oca& item
+        );
+        /*!
+            ensures
+                - #get_oca() == item 
+        !*/
+
+        const oca get_oca (
+        ) const;
+        /*!
+            ensures
+                - returns a copy of the optimizer used to solve the SVM problem.  
+        !*/
+
+        const kernel_type get_kernel (
+        ) const;
+        /*!
+            ensures
+                - returns a copy of the kernel function in use by this object.  Since
+                  the linear kernels don't have any parameters this function just
+                  returns kernel_type()
+        !*/
+
+        void set_c (
+            scalar_type C
+        );
+        /*!
+            requires
+                - C > 0
+            ensures
+                - #get_c() == C 
+        !*/
+
+        const scalar_type get_c (
+        ) const;
+        /*!
+            ensures
+                - returns the SVM regularization parameter.  It is the parameter that 
+                  determines the trade off between trying to fit the training data 
+                  exactly or allowing more errors but hopefully improving the 
+                  generalization of the resulting classifier.  Larger values encourage 
+                  exact fitting while smaller values of C may encourage better 
+                  generalization. 
+        !*/
+
+        trained_function_type train (
+            const std::vector<sample_type>& all_samples,
+            const std::vector<label_type>& all_labels
+        ) const;
+        /*!
+            requires
+                - is_learning_problem(all_samples, all_labels)
+            ensures
+                - trains a multiclass SVM to solve the given multiclass classification problem.  
+                - returns a multiclass_linear_decision_function F with the following properties:
+                    - if (new_x is a sample predicted to have a label of L) then
+                        - F(new_x) == L
+                    - F.get_labels() == select_all_distinct_labels(all_labels)
+                    - F.number_of_classes() == select_all_distinct_labels(all_labels).size()
+        !*/
+
+        trained_function_type train (
+            const std::vector<sample_type>& all_samples,
+            const std::vector<label_type>& all_labels,
+            scalar_type& svm_objective
+        ) const;
+        /*!
+            requires
+                - is_learning_problem(all_samples, all_labels)
+            ensures
+                - trains a multiclass SVM to solve the given multiclass classification problem.  
+                - returns a multiclass_linear_decision_function F with the following properties:
+                    - if (new_x is a sample predicted to have a label of L) then
+                        - F(new_x) == L
+                    - F.get_labels() == select_all_distinct_labels(all_labels)
+                    - F.number_of_classes() == select_all_distinct_labels(all_labels).size()
+                - #svm_objective == the final value of the SVM objective function
+        !*/
+
+    };
+
+// ----------------------------------------------------------------------------------------
+
+}
+
+
+#endif // DLIB_SVm_MULTICLASS_LINEAR_TRAINER_ABSTRACT_H__
+
+