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// Copyright (C) 2010 Davis E. King (davis@dlib.net)
// License: Boost Software License See LICENSE.txt for the full license.
#undef DLIB_ONE_VS_ALL_TRAiNER_ABSTRACT_Hh_
#ifdef DLIB_ONE_VS_ALL_TRAiNER_ABSTRACT_Hh_
#include "one_vs_all_decision_function_abstract.h"
#include <vector>
#include "../any/any_trainer_abstract.h"
namespace dlib
{
// ----------------------------------------------------------------------------------------
template <
typename any_trainer,
typename label_type_ = double
>
class one_vs_all_trainer
{
/*!
REQUIREMENTS ON any_trainer
must be an instantiation of the dlib::any_trainer template.
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<<.
WHAT THIS OBJECT REPRESENTS
This object is a tool for turning a bunch of binary classifiers into a
multiclass classifier. It does this by training the binary classifiers
in a one vs. all fashion. That is, if you have N possible classes then
it trains N binary classifiers which are then used to vote on the identity
of a test sample.
This object works with any kind of binary classification trainer object
capable of being assigned to an any_trainer object. (e.g. the svm_nu_trainer)
!*/
public:
typedef label_type_ label_type;
typedef typename any_trainer::sample_type sample_type;
typedef typename any_trainer::scalar_type scalar_type;
typedef typename any_trainer::mem_manager_type mem_manager_type;
typedef one_vs_all_decision_function<one_vs_all_trainer> trained_function_type;
one_vs_all_trainer (
);
/*!
ensures
- This object is properly initialized.
- This object will not be verbose unless be_verbose() is called.
- No binary trainers are associated with *this. I.e. you have to
call set_trainer() before calling train().
- #get_num_threads() == 4
!*/
void set_trainer (
const any_trainer& trainer
);
/*!
ensures
- sets the trainer used for all binary subproblems. Any previous
calls to set_trainer() are overridden by this function. Even the
more specific set_trainer(trainer, l) form.
!*/
void set_trainer (
const any_trainer& trainer,
const label_type& l
);
/*!
ensures
- Sets the trainer object used to create a binary classifier to
distinguish l labeled samples from all other samples.
!*/
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_num_threads (
unsigned long num
);
/*!
ensures
- #get_num_threads() == num
!*/
unsigned long get_num_threads (
) const;
/*!
ensures
- returns the number of threads used during training. You should
usually set this equal to the number of processing cores on your
machine.
!*/
struct invalid_label : public dlib::error
{
/*!
This is the exception thrown by the train() function below.
!*/
label_type l;
};
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 bunch of binary classifiers in a one vs all fashion to solve the given
multiclass classification problem.
- returns a one_vs_all_decision_function F with the following properties:
- F contains all the learned binary classifiers and can be used to predict
the labels of new samples.
- 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()
throws
- invalid_label
This exception is thrown if there are labels in all_labels which don't have
any corresponding trainer object. This will never happen if set_trainer(trainer)
has been called. However, if only the set_trainer(trainer,l) form has been
used then this exception is thrown if not all labels have been given a trainer.
invalid_label::l will contain the label which is missing a trainer object.
Additionally, the exception will contain an informative error message available
via invalid_label::what().
!*/
};
// ----------------------------------------------------------------------------------------
}
#endif // DLIB_ONE_VS_ALL_TRAiNER_ABSTRACT_Hh_
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