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LogisticRegression Class Reference

Implements Logistic Regression classifier. More...

#include <ml.hpp>

Inherits cv::ml::StatModel.

Public Types

enum  RegKinds { REG_DISABLE = -1, REG_L1 = 0, REG_L2 = 1 }
 

Regularization kinds.

More...
enum  Methods { , MINI_BATCH = 1 }
 

Training methods.

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enum  Flags { , RAW_OUTPUT = 1 }
 

Predict options.

More...

Public Member Functions

virtual CV_WRAP double getLearningRate () const =0
 Learning rate.
virtual CV_WRAP void setLearningRate (double val)=0
 

Learning rate.


virtual CV_WRAP int getIterations () const =0
 Number of iterations.
virtual CV_WRAP void setIterations (int val)=0
 

Number of iterations.


virtual CV_WRAP int getRegularization () const =0
 Kind of regularization to be applied.
virtual CV_WRAP void setRegularization (int val)=0
 

Kind of regularization to be applied.


virtual CV_WRAP int getTrainMethod () const =0
 Kind of training method used.
virtual CV_WRAP void setTrainMethod (int val)=0
 

Kind of training method used.


virtual CV_WRAP int getMiniBatchSize () const =0
 Specifies the number of training samples taken in each step of Mini-Batch Gradient Descent.
virtual CV_WRAP void setMiniBatchSize (int val)=0
 

Specifies the number of training samples taken in each step of Mini-Batch Gradient Descent.


virtual CV_WRAP TermCriteria getTermCriteria () const =0
 Termination criteria of the algorithm.
virtual CV_WRAP void setTermCriteria (TermCriteria val)=0
 

Termination criteria of the algorithm.


virtual CV_WRAP float predict (InputArray samples, OutputArray results=noArray(), int flags=0) const =0
 Predicts responses for input samples and returns a float type.
virtual CV_WRAP Mat get_learnt_thetas () const =0
 This function returns the trained paramters arranged across rows.
virtual CV_WRAP int getVarCount () const =0
 Returns the number of variables in training samples.
virtual CV_WRAP bool empty () const
 Returns true if the Algorithm is empty (e.g.
virtual CV_WRAP bool isTrained () const =0
 Returns true if the model is trained.
virtual CV_WRAP bool isClassifier () const =0
 Returns true if the model is classifier.
virtual CV_WRAP bool train (const Ptr< TrainData > &trainData, int flags=0)
 Trains the statistical model.
virtual CV_WRAP bool train (InputArray samples, int layout, InputArray responses)
 Trains the statistical model.
virtual CV_WRAP float calcError (const Ptr< TrainData > &data, bool test, OutputArray resp) const
 Computes error on the training or test dataset.
virtual CV_WRAP void clear ()
 Clears the algorithm state.
virtual void write (FileStorage &fs) const
 Stores algorithm parameters in a file storage.
virtual void read (const FileNode &fn)
 Reads algorithm parameters from a file storage.
virtual CV_WRAP void save (const String &filename) const
 Saves the algorithm to a file.
virtual CV_WRAP String getDefaultName () const
 Returns the algorithm string identifier.

Static Public Member Functions

static CV_WRAP Ptr
< LogisticRegression
create ()
 Creates empty model.
template<typename _Tp >
static Ptr< _Tp > train (const Ptr< TrainData > &data, int flags=0)
 Create and train model with default parameters.
template<typename _Tp >
static Ptr< _Tp > read (const FileNode &fn)
 Reads algorithm from the file node.
template<typename _Tp >
static Ptr< _Tp > load (const String &filename, const String &objname=String())
 Loads algorithm from the file.
template<typename _Tp >
static Ptr< _Tp > loadFromString (const String &strModel, const String &objname=String())
 Loads algorithm from a String.

Detailed Description

Implements Logistic Regression classifier.

See also:
ml_intro_lr

Definition at line 1402 of file ml.hpp.


Member Enumeration Documentation

enum Flags [inherited]

Predict options.

Enumerator:
RAW_OUTPUT 

makes the method return the raw results (the sum), not the class label

Reimplemented in DTrees.

Definition at line 296 of file ml.hpp.

enum Methods

Training methods.

Enumerator:
MINI_BATCH 

Set MiniBatchSize to a positive integer when using this method.

Definition at line 1452 of file ml.hpp.

enum RegKinds

Regularization kinds.

Enumerator:
REG_DISABLE 

Regularization disabled.

REG_L1 

L1 norm

REG_L2 

L2 norm

Definition at line 1445 of file ml.hpp.


Member Function Documentation

virtual CV_WRAP float calcError ( const Ptr< TrainData > &  data,
bool  test,
OutputArray  resp 
) const [virtual, inherited]

Computes error on the training or test dataset.

Parameters:
datathe training data
testif true, the error is computed over the test subset of the data, otherwise it's computed over the training subset of the data. Please note that if you loaded a completely different dataset to evaluate already trained classifier, you will probably want not to set the test subset at all with TrainData::setTrainTestSplitRatio and specify test=false, so that the error is computed for the whole new set. Yes, this sounds a bit confusing.
respthe optional output responses.

The method uses StatModel::predict to compute the error. For regression models the error is computed as RMS, for classifiers - as a percent of missclassified samples (0-100%).

virtual CV_WRAP void clear (  ) [virtual, inherited]

Clears the algorithm state.

Reimplemented in DescriptorMatcher, and FlannBasedMatcher.

Definition at line 2984 of file core.hpp.

static CV_WRAP Ptr<LogisticRegression> create (  ) [static]

Creates empty model.

Creates Logistic Regression model with parameters given.

virtual CV_WRAP bool empty (  ) const [virtual, inherited]

Returns true if the Algorithm is empty (e.g.

in the very beginning or after unsuccessful read

Reimplemented from Algorithm.

virtual CV_WRAP Mat get_learnt_thetas (  ) const [pure virtual]

This function returns the trained paramters arranged across rows.

For a two class classifcation problem, it returns a row matrix. It returns learnt paramters of the Logistic Regression as a matrix of type CV_32F.

virtual CV_WRAP String getDefaultName (  ) const [virtual, inherited]

Returns the algorithm string identifier.

This string is used as top level xml/yml node tag when the object is saved to a file or string.

virtual CV_WRAP int getIterations (  ) const [pure virtual]

Number of iterations.

See also:
setIterations
virtual CV_WRAP double getLearningRate (  ) const [pure virtual]

Learning rate.

See also:
setLearningRate
virtual CV_WRAP int getMiniBatchSize (  ) const [pure virtual]

Specifies the number of training samples taken in each step of Mini-Batch Gradient Descent.

Will only be used if using LogisticRegression::MINI_BATCH training algorithm. It has to take values less than the total number of training samples.

See also:
setMiniBatchSize
virtual CV_WRAP int getRegularization (  ) const [pure virtual]

Kind of regularization to be applied.

See LogisticRegression::RegKinds.

See also:
setRegularization
virtual CV_WRAP TermCriteria getTermCriteria (  ) const [pure virtual]

Termination criteria of the algorithm.

See also:
setTermCriteria
virtual CV_WRAP int getTrainMethod (  ) const [pure virtual]

Kind of training method used.

See LogisticRegression::Methods.

See also:
setTrainMethod
virtual CV_WRAP int getVarCount (  ) const [pure virtual, inherited]

Returns the number of variables in training samples.

virtual CV_WRAP bool isClassifier (  ) const [pure virtual, inherited]

Returns true if the model is classifier.

virtual CV_WRAP bool isTrained (  ) const [pure virtual, inherited]

Returns true if the model is trained.

static Ptr<_Tp> load ( const String &  filename,
const String &  objname = String() 
) [static, inherited]

Loads algorithm from the file.

Parameters:
filenameName of the file to read.
objnameThe optional name of the node to read (if empty, the first top-level node will be used)

This is static template method of Algorithm. It's usage is following (in the case of SVM):

     Ptr<SVM> svm = Algorithm::load<SVM>("my_svm_model.xml");

In order to make this method work, the derived class must overwrite Algorithm::read(const FileNode& fn).

Definition at line 3027 of file core.hpp.

static Ptr<_Tp> loadFromString ( const String &  strModel,
const String &  objname = String() 
) [static, inherited]

Loads algorithm from a String.

Parameters:
strModelThe string variable containing the model you want to load.
objnameThe optional name of the node to read (if empty, the first top-level node will be used)

This is static template method of Algorithm. It's usage is following (in the case of SVM):

     Ptr<SVM> svm = Algorithm::loadFromString<SVM>(myStringModel);

Definition at line 3046 of file core.hpp.

virtual CV_WRAP float predict ( InputArray  samples,
OutputArray  results = noArray(),
int  flags = 0 
) const [pure virtual]

Predicts responses for input samples and returns a float type.

Parameters:
samplesThe input data for the prediction algorithm. Matrix [m x n], where each row contains variables (features) of one object being classified. Should have data type CV_32F.
resultsPredicted labels as a column matrix of type CV_32S.
flagsNot used.

Implements StatModel.

virtual void read ( const FileNode fn ) [virtual, inherited]

Reads algorithm parameters from a file storage.

Reimplemented in DescriptorMatcher, and FlannBasedMatcher.

Definition at line 2992 of file core.hpp.

static Ptr<_Tp> read ( const FileNode fn ) [static, inherited]

Reads algorithm from the file node.

This is static template method of Algorithm. It's usage is following (in the case of SVM):

     Ptr<SVM> svm = Algorithm::read<SVM>(fn);

In order to make this method work, the derived class must overwrite Algorithm::read(const FileNode& fn) and also have static create() method without parameters (or with all the optional parameters)

Reimplemented in DescriptorMatcher, and FlannBasedMatcher.

Definition at line 3008 of file core.hpp.

virtual CV_WRAP void save ( const String &  filename ) const [virtual, inherited]

Saves the algorithm to a file.

In order to make this method work, the derived class must implement Algorithm::write(FileStorage& fs).

virtual CV_WRAP void setIterations ( int  val ) [pure virtual]

Number of iterations.

See also:
getIterations
virtual CV_WRAP void setLearningRate ( double  val ) [pure virtual]

Learning rate.

See also:
getLearningRate
virtual CV_WRAP void setMiniBatchSize ( int  val ) [pure virtual]

Specifies the number of training samples taken in each step of Mini-Batch Gradient Descent.

See also:
getMiniBatchSize
virtual CV_WRAP void setRegularization ( int  val ) [pure virtual]

Kind of regularization to be applied.

See also:
getRegularization
virtual CV_WRAP void setTermCriteria ( TermCriteria  val ) [pure virtual]

Termination criteria of the algorithm.

See also:
getTermCriteria
virtual CV_WRAP void setTrainMethod ( int  val ) [pure virtual]

Kind of training method used.

See also:
getTrainMethod
static Ptr<_Tp> train ( const Ptr< TrainData > &  data,
int  flags = 0 
) [static, inherited]

Create and train model with default parameters.

The class must implement static `create()` method with no parameters or with all default parameter values

Definition at line 357 of file ml.hpp.

virtual CV_WRAP bool train ( InputArray  samples,
int  layout,
InputArray  responses 
) [virtual, inherited]

Trains the statistical model.

Parameters:
samplestraining samples
layoutSee ml::SampleTypes.
responsesvector of responses associated with the training samples.
virtual CV_WRAP bool train ( const Ptr< TrainData > &  trainData,
int  flags = 0 
) [virtual, inherited]

Trains the statistical model.

Parameters:
trainDatatraining data that can be loaded from file using TrainData::loadFromCSV or created with TrainData::create.
flagsoptional flags, depending on the model. Some of the models can be updated with the new training samples, not completely overwritten (such as NormalBayesClassifier or ANN_MLP).
virtual void write ( FileStorage fs ) const [virtual, inherited]

Stores algorithm parameters in a file storage.

Reimplemented in DescriptorMatcher, and FlannBasedMatcher.

Definition at line 2988 of file core.hpp.