PLearn::ClassErrorCostFunction Class Reference

#include <ClassErrorCostFunction.h>

Inheritance diagram for PLearn::ClassErrorCostFunction:

[legend]Collaboration diagram for PLearn::ClassErrorCostFunction:

[legend]List of all members.

Public Member Functions
	ClassErrorCostFunction (bool the_output_is_classnum=false)
	PLEARN_DECLARE_OBJECT (ClassErrorCostFunction)
virtual string	info () const
	returns a bit more informative string about object (default returns classname())
virtual real	evaluate (const Vec &output, const Vec &target) const
	returns K(x1,x2)
Static Protected Member Functions
void	declareOptions (OptionList &ol)
	recognized option is "output_is_classnum"
Protected Attributes
bool	output_is_classnum
Private Types
typedef Kernel	inherited

---

Detailed Description

* If output and target both have length 1, then binary classification with targets -1 and +1 is assumed and the sign of the output is considered If output has length>1 and target has length 1, then output is understood as giving a score for each class while target is the index of the correct class (numbered from 0) If both output and target have a length>1 then then output is understood as giving a score for each class while the correct class is given by argmax(target) In any case, evaluation returns 0 if classification was correct, 1 otherwise

Definition at line 64 of file ClassErrorCostFunction.h.

---

Member Typedef Documentation

typedef Kernel PLearn::ClassErrorCostFunction::inherited [private]

Reimplemented from PLearn::Kernel. Definition at line 66 of file ClassErrorCostFunction.h.

---

Constructor & Destructor Documentation

PLearn::ClassErrorCostFunction::ClassErrorCostFunction (  bool  the_output_is_classnum = false  )  [inline]

There are several cases: 1) target is a single value +1 or -1 , and output is a single value whose sign stands for the class 2) target is a single value in 0..n-1 indicating classnumber and output is a n-dimensional vector of scores 3) target is a n-dimensional vector whose argmax indicates the class, and output is a n-dimensional vector of scores 4) target is a single value indicating classnumber, and output is a single value indicating classnumber 5) target is a single value 0 or 1 , and output is a single value with the threshold 0.5 Cases 1,2,3 are handled correctly with the default output_is_classnum=false For case 4 and 5, you must specify output_is_classnum=true Definition at line 81 of file ClassErrorCostFunction.h. References output_is_classnum.

---

Member Function Documentation

void PLearn::ClassErrorCostFunction::declareOptions (  OptionList &  ol  )  [static, protected]

recognized option is "output_is_classnum" Reimplemented from PLearn::Kernel. Definition at line 85 of file ClassErrorCostFunction.cc. References PLearn::declareOption(), and PLearn::OptionList.

real PLearn::ClassErrorCostFunction::evaluate (  const Vec &  output, const Vec &  target )  const [virtual]

returns K(x1,x2) Implements PLearn::Kernel. Definition at line 53 of file ClassErrorCostFunction.cc. References PLearn::argmax(), PLearn::is_integer(), PLearn::TVec< T >::length(), output_is_classnum, and PLearn::Vec.

virtual string PLearn::ClassErrorCostFunction::info (   )  const [inline, virtual]

returns a bit more informative string about object (default returns classname()) Reimplemented from PLearn::Object. Definition at line 86 of file ClassErrorCostFunction.h.

PLearn::ClassErrorCostFunction::PLEARN_DECLARE_OBJECT (  ClassErrorCostFunction   )

---

Member Data Documentation

bool PLearn::ClassErrorCostFunction::output_is_classnum [protected]

Definition at line 69 of file ClassErrorCostFunction.h. Referenced by ClassErrorCostFunction(), and evaluate().

---

The documentation for this class was generated from the following files:

• ClassErrorCostFunction.h
• ClassErrorCostFunction.cc

---