org.tribuo.common.liblinear

Class LibLinearModel<T extends Output<T>>

java.lang.Object

org.tribuo.Model<T>

org.tribuo.common.liblinear.LibLinearModel<T>

All Implemented Interfaces:

com.oracle.labs.mlrg.olcut.provenance.Provenancable<ModelProvenance>, Serializable

Direct Known Subclasses:

LibLinearClassificationModel, LibLinearRegressionModel

public abstract class LibLinearModel<T extends Output<T>>
extends Model<T>

A Model which wraps a LibLinear-java model.

It disables the LibLinear debug output as it's very chatty.

See:

 Fan RE, Chang KW, Hsieh CJ, Wang XR, Lin CJ.
 "LIBLINEAR: A library for Large Linear Classification"
 Journal of Machine Learning Research, 2008.
 

and for the original algorithm:

 Cortes C, Vapnik V.
 "Support-Vector Networks"
 Machine Learning, 1995.
 

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected List<de.bwaldvogel.liblinear.Model>	models The list of LibLinear models.

Fields inherited from class org.tribuo.Model

ALL_OUTPUTS, BIAS_FEATURE, featureIDMap, generatesProbabilities, name, outputIDInfo, provenance, provenanceOutput

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	LibLinearModel(String name, ModelProvenance description, ImmutableFeatureMap featureIDMap, ImmutableOutputInfo<T> labelIDMap, boolean generatesProbabilities, List<de.bwaldvogel.liblinear.Model> models) Constructs a LibLinear model from the supplied arguments.

Method Summary

Modifier and Type	Method and Description
protected static de.bwaldvogel.liblinear.Model	copyModel(de.bwaldvogel.liblinear.Model model) Copies the model by writing it out to a String and loading it back in.
Optional<Excuse<T>>	getExcuse(Example<T> e) This call is expensive as it copies out the weight matrix from the LibLinear model.
Optional<List<Excuse<T>>>	getExcuses(Iterable<Example<T>> examples) Generates an excuse for each example.
protected abstract double[][]	getFeatureWeights() Extracts the feature weights from the models.
List<de.bwaldvogel.liblinear.Model>	getInnerModels() Returns an unmodifiable list containing a copy of each model.
protected abstract Excuse<T>	innerGetExcuse(Example<T> e, double[][] featureWeights) The call to getFeatureWeights in the public methods copies the weights array so this inner method exists to save the copy in getExcuses.

Methods inherited from class org.tribuo.Model

copy, copy, generatesProbabilities, getFeatureIDMap, getName, getOutputIDInfo, getProvenance, getTopFeatures, innerPredict, predict, predict, predict, setName, toString, validate

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

models

protected final List<de.bwaldvogel.liblinear.Model> models

The list of LibLinear models. Multiple models are used by multi-label and multidimensional regression outputs.

Constructor Detail

LibLinearModel

protected LibLinearModel(String name,
                         ModelProvenance description,
                         ImmutableFeatureMap featureIDMap,
                         ImmutableOutputInfo<T> labelIDMap,
                         boolean generatesProbabilities,
                         List<de.bwaldvogel.liblinear.Model> models)

Constructs a LibLinear model from the supplied arguments.

Parameters:

name - The model name.

description - The model provenance.

featureIDMap - The features this model knows about.

labelIDMap - The outputs this model produces.

generatesProbabilities - Does this model generate probabilities?

models - The liblinear models themselves.

Method Detail

getInnerModels

public List<de.bwaldvogel.liblinear.Model> getInnerModels()

Returns an unmodifiable list containing a copy of each model.

As liblinear-java models don't expose a copy constructor this requires serializing each model to a String and rebuilding it, and is thus quite expensive.

Returns:

A copy of all of the models.

getExcuse

public Optional<Excuse<T>> getExcuse(Example<T> e)

This call is expensive as it copies out the weight matrix from the LibLinear model.

Prefer getExcuses(java.lang.Iterable<org.tribuo.Example<T>>) to get multiple excuses.

Specified by:

getExcuse in class Model<T extends Output<T>>

Parameters:

e - The example to excuse.

Returns:

An Excuse for this example.

getExcuses

public Optional<List<Excuse<T>>> getExcuses(Iterable<Example<T>> examples)

Description copied from class: Model

Generates an excuse for each example.

This may be an expensive operation, and probably should be overridden in subclasses for performance reasons.

These excuses either contain per class information or an entry with key Model.ALL_OUTPUTS.

The optional is empty if the model does not provide excuses.

Overrides:

getExcuses in class Model<T extends Output<T>>

Parameters:

examples - An iterable of examples

Returns:

A optional list of excuses. The Optional is empty if this model does not provide excuses.

copyModel

protected static de.bwaldvogel.liblinear.Model copyModel(de.bwaldvogel.liblinear.Model model)

Copies the model by writing it out to a String and loading it back in.

Unfortunately liblinear-java doesn't have a copy constructor on it's model.

Parameters:

model - The model to copy.

Returns:

A deep copy of the model.

getFeatureWeights

protected abstract double[][] getFeatureWeights()

Extracts the feature weights from the models. The first dimension corresponds to the model index.

Returns:

The feature weights.

innerGetExcuse

protected abstract Excuse<T> innerGetExcuse(Example<T> e,
                                            double[][] featureWeights)

The call to getFeatureWeights in the public methods copies the weights array so this inner method exists to save the copy in getExcuses.

If it becomes a problem then we could cache the feature weights in the model.

Parameters:

e - The example.

featureWeights - The per dimension feature weights.

Returns:

An excuse for this example.