SPegasos

java.lang.Object
- weka.classifiers.Classifier
- - weka.classifiers.functions.SPegasos

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable, UpdateableClassifier, CapabilitiesHandler, OptionHandler, RevisionHandler, TechnicalInformationHandler
```
public class SPegasos
extends Classifier
implements TechnicalInformationHandler, UpdateableClassifier, OptionHandler
```
Implements the stochastic variant of the Pegasos (Primal Estimated sub-GrAdient SOlver for SVM) method of Shalev-Shwartz et al. (2007). This implementation globally replaces all missing values and transforms nominal attributes into binary ones. It also normalizes all attributes, so the coefficients in the output are based on the normalized data. For more information, see

S. Shalev-Shwartz, Y. Singer, N. Srebro: Pegasos: Primal Estimated sub-GrAdient SOlver for SVM. In: 24th International Conference on MachineLearning, 807-814, 2007.
BibTeX:
```
 @inproceedings{Shalev-Shwartz2007,
    author = {S. Shalev-Shwartz and Y. Singer and N. Srebro},
    booktitle = {24th International Conference on MachineLearning},
    pages = {807-814},
    title = {Pegasos: Primal Estimated sub-GrAdient SOlver for SVM},
    year = {2007}
 }
 
```
Valid options are:
```
 -L <double>
  The lambda regularization constant (default = 0.0001)
```
```
 -E <integer>
  The number of epochs to perform (batch learning only, default = 500)
```
```
 -N
  Don't normalize the data
```
```
 -M
  Don't replace missing values
```
Version:

$Revision: 6580 $

Author:

Mark Hall (mhall{[at]}pentaho{[dot]}com)

See Also:

Serialized Form

Field Summary

Fields
Modifier and Type Field and Description

static Tag[] TAGS_SELECTION
Loss functions to choose from

Fields
Modifier and Type	Field and Description
`static Tag[]`	`TAGS_SELECTION` Loss functions to choose from

Constructor Summary

Constructors
Constructor and Description

SPegasos()

Constructors
Constructor and Description
`SPegasos()`

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`buildClassifier(Instances data)` Method for building the classifier.
`double[]`	`distributionForInstance(Instance inst)` Computes the distribution for a given instance
`java.lang.String`	`dontNormalizeTipText()` Returns the tip text for this property
`java.lang.String`	`dontReplaceMissingTipText()` Returns the tip text for this property
`java.lang.String`	`epochsTipText()` Returns the tip text for this property
`Capabilities`	`getCapabilities()` Returns default capabilities of the classifier.
`boolean`	`getDontNormalize()` Get whether normalization has been turned off.
`boolean`	`getDontReplaceMissing()` Get whether global replacement of missing values has been disabled.
`int`	`getEpochs()` Get current number of epochs
`double`	`getLambda()` Get the current value of lambda
`SelectedTag`	`getLossFunction()` Get the current loss function.
`java.lang.String[]`	`getOptions()` Gets the current settings of the classifier.
`java.lang.String`	`getRevision()` Returns the revision string.
`TechnicalInformation`	`getTechnicalInformation()` Returns an instance of a TechnicalInformation object, containing detailed information about the technical background of this class, e.g., paper reference or book this class is based on.
`java.lang.String`	`globalInfo()` Returns a string describing classifier
`java.lang.String`	`lambdaTipText()` Returns the tip text for this property
`java.util.Enumeration<Option>`	`listOptions()` Returns an enumeration describing the available options.
`java.lang.String`	`lossFunctionTipText()` Returns the tip text for this property
`static void`	`main(java.lang.String[] args)` Main method for testing this class.
`void`	`reset()` Reset the classifier.
`void`	`setDontNormalize(boolean m)` Turn normalization off/on.
`void`	`setDontReplaceMissing(boolean m)` Turn global replacement of missing values off/on.
`void`	`setEpochs(int e)` Set the number of epochs to use
`void`	`setLambda(double lambda)` Set the value of lambda to use
`void`	`setLossFunction(SelectedTag function)` Set the loss function to use.
`void`	`setOptions(java.lang.String[] options)` Parses a given list of options.
`java.lang.String`	`toString()` Prints out the classifier.
`void`	`updateClassifier(Instance instance)` Updates the classifier with the given instance.

Methods inherited from class weka.classifiers.Classifier
classifyInstance, debugTipText, forName, getDebug, makeCopies, makeCopy, setDebug

Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Field Detail
  - TAGS_SELECTION
```
public static final Tag[] TAGS_SELECTION
```
    Loss functions to choose from
- Constructor Detail
  - SPegasos
```
public SPegasos()
```
- Method Detail
  - getCapabilities
```
public Capabilities getCapabilities()
```
    Returns default capabilities of the classifier.
    
    Specified by:
    
    getCapabilities in interface CapabilitiesHandler
    
    Overrides:
    
    getCapabilities in class Classifier
    
    Returns:
    
    the capabilities of this classifier
    
    See Also:
    
    Capabilities
  - lambdaTipText
```
public java.lang.String lambdaTipText()
```
    Returns the tip text for this property
    
    Returns:
    
    tip text for this property suitable for displaying in the explorer/experimenter gui
  - setLambda
```
public void setLambda(double lambda)
```
    Set the value of lambda to use
    
    Parameters:
    
    lambda - the value of lambda to use
  - getLambda
```
public double getLambda()
```
    Get the current value of lambda
    
    Returns:
    
    the current value of lambda
  - epochsTipText
```
public java.lang.String epochsTipText()
```
    Returns the tip text for this property
    
    Returns:
    
    tip text for this property suitable for displaying in the explorer/experimenter gui
  - setEpochs
```
public void setEpochs(int e)
```
    Set the number of epochs to use
    
    Parameters:
    
    e - the number of epochs to use
  - getEpochs
```
public int getEpochs()
```
    Get current number of epochs
    
    Returns:
    
    the current number of epochs
  - setDontNormalize
```
public void setDontNormalize(boolean m)
```
    Turn normalization off/on.
    
    Parameters:
    
    m - true if normalization is to be disabled.
  - getDontNormalize
```
public boolean getDontNormalize()
```
    Get whether normalization has been turned off.
    
    Returns:
    
    true if normalization has been disabled.
  - dontNormalizeTipText
```
public java.lang.String dontNormalizeTipText()
```
    Returns the tip text for this property
    
    Returns:
    
    tip text for this property suitable for displaying in the explorer/experimenter gui
  - setDontReplaceMissing
```
public void setDontReplaceMissing(boolean m)
```
    Turn global replacement of missing values off/on. If turned off, then missing values are effectively ignored.
    
    Parameters:
    
    m - true if global replacement of missing values is to be turned off.
  - getDontReplaceMissing
```
public boolean getDontReplaceMissing()
```
    Get whether global replacement of missing values has been disabled.
    
    Returns:
    
    true if global replacement of missing values has been turned off
  - dontReplaceMissingTipText
```
public java.lang.String dontReplaceMissingTipText()
```
    Returns the tip text for this property
    
    Returns:
    
    tip text for this property suitable for displaying in the explorer/experimenter gui
  - setLossFunction
```
public void setLossFunction(SelectedTag function)
```
    Set the loss function to use.
    
    Parameters:
    
    function - the loss function to use.
  - getLossFunction
```
public SelectedTag getLossFunction()
```
    Get the current loss function.
    
    Returns:
    
    the current loss function.
  - lossFunctionTipText
```
public java.lang.String lossFunctionTipText()
```
    Returns the tip text for this property
    
    Returns:
    
    tip text for this property suitable for displaying in the explorer/experimenter gui
  - listOptions
```
public java.util.Enumeration<Option> listOptions()
```
    Returns an enumeration describing the available options.
    
    Specified by:
    
    listOptions in interface OptionHandler
    
    Overrides:
    
    listOptions in class Classifier
    
    Returns:
    
    an enumeration of all the available options.
  - setOptions
```
public void setOptions(java.lang.String[] options)
                throws java.lang.Exception
```
    Parses a given list of options.
    Valid options are:
```
 -L <double>
  The lambda regularization constant (default = 0.0001)
```
```
 -E <integer>
  The number of epochs to perform (batch learning only, default = 500)
```
```
 -N
  Don't normalize the data
```
```
 -M
  Don't replace missing values
```
    Specified by:
    
    setOptions in interface OptionHandler
    
    Overrides:
    
    setOptions in class Classifier
    
    Parameters:
    
    options - the list of options as an array of strings
    
    Throws:
    
    java.lang.Exception - if an option is not supported
  - getOptions
```
public java.lang.String[] getOptions()
```
    Gets the current settings of the classifier.
    
    Specified by:
    
    getOptions in interface OptionHandler
    
    Overrides:
    
    getOptions in class Classifier
    
    Returns:
    
    an array of strings suitable for passing to setOptions
  - globalInfo
```
public java.lang.String globalInfo()
```
    Returns a string describing classifier
    
    Returns:
    
    a description suitable for displaying in the explorer/experimenter gui
  - getTechnicalInformation
```
public TechnicalInformation getTechnicalInformation()
```
    Returns an instance of a TechnicalInformation object, containing detailed information about the technical background of this class, e.g., paper reference or book this class is based on.
    
    Specified by:
    
    getTechnicalInformation in interface TechnicalInformationHandler
    
    Returns:
    
    the technical information about this class
  - reset
```
public void reset()
```
    Reset the classifier.
  - buildClassifier
```
public void buildClassifier(Instances data)
                     throws java.lang.Exception
```
    Method for building the classifier.
    
    Specified by:
    
    buildClassifier in class Classifier
    
    Parameters:
    
    data - the set of training instances.
    
    Throws:
    
    java.lang.Exception - if the classifier can't be built successfully.
  - updateClassifier
```
public void updateClassifier(Instance instance)
                      throws java.lang.Exception
```
    Updates the classifier with the given instance.
    
    Specified by:
    
    updateClassifier in interface UpdateableClassifier
    
    Parameters:
    
    instance - the new training instance to include in the model
    
    Throws:
    
    java.lang.Exception - if the instance could not be incorporated in the model.
  - distributionForInstance
```
public double[] distributionForInstance(Instance inst)
                                 throws java.lang.Exception
```
    Computes the distribution for a given instance
    
    Overrides:
    
    distributionForInstance in class Classifier
    
    Parameters:
    
    instance - the instance for which distribution is computed
    
    Returns:
    
    the distribution
    
    Throws:
    
    java.lang.Exception - if the distribution can't be computed successfully
  - toString
```
public java.lang.String toString()
```
    Prints out the classifier.
    
    Overrides:
    
    toString in class java.lang.Object
    
    Returns:
    
    a description of the classifier as a string
  - getRevision
```
public java.lang.String getRevision()
```
    Returns the revision string.
    
    Specified by:
    
    getRevision in interface RevisionHandler
    
    Overrides:
    
    getRevision in class Classifier
    
    Returns:
    
    the revision
  - main
```
public static void main(java.lang.String[] args)
```
    Main method for testing this class.

Class SPegasos

Field Summary

Constructor Summary

Method Summary

Methods inherited from class weka.classifiers.Classifier

Methods inherited from class java.lang.Object

Field Detail

TAGS_SELECTION

Constructor Detail

SPegasos

Method Detail

getCapabilities

lambdaTipText

setLambda

getLambda

epochsTipText

setEpochs

getEpochs

setDontNormalize

getDontNormalize

dontNormalizeTipText

setDontReplaceMissing

getDontReplaceMissing

dontReplaceMissingTipText

setLossFunction

getLossFunction

lossFunctionTipText

listOptions

setOptions

getOptions

globalInfo

getTechnicalInformation

reset

buildClassifier

updateClassifier

distributionForInstance

toString

getRevision

main