org.tribuo.classification.sgd.kernel

Class KernelSVMTrainer

java.lang.Object

org.tribuo.classification.sgd.kernel.KernelSVMTrainer

All Implemented Interfaces:

com.oracle.labs.mlrg.olcut.config.Configurable, com.oracle.labs.mlrg.olcut.provenance.Provenancable<TrainerProvenance>, Trainer<Label>, WeightedExamples

public class KernelSVMTrainer
extends Object
implements Trainer<Label>, WeightedExamples

A trainer for a kernelised model using the Pegasos optimiser.

The Pegasos optimiser is extremely sensitive to the lambda parameter, and this value must be tuned to get good performance.

See:

 Shalev-Shwartz S, Singer Y, Srebro N, Cotter A
 "Pegasos: Primal Estimated Sub-Gradient Solver for SVM"
 Mathematical Programming, 2011.
 

Field Summary

Fields inherited from interface org.tribuo.Trainer

DEFAULT_SEED

Constructor Summary

Constructors

Constructor and Description
KernelSVMTrainer(Kernel kernel, double lambda, int epochs, int loggingInterval, long seed) Constructs a trainer for a kernel SVM model.
KernelSVMTrainer(Kernel kernel, double lambda, int epochs, long seed) Constructs a trainer for a kernel SVM model.

Method Summary

Modifier and Type	Method and Description
int	getInvocationCount() The number of times this trainer instance has had it's train method invoked.
TrainerProvenance	getProvenance()
void	postConfig() Used by the OLCUT configuration system, and should not be called by external code.
void	setShuffle(boolean shuffle) Turn on or off shuffling of examples.
String	toString()
KernelSVMModel	train(Dataset<Label> examples, Map<String,com.oracle.labs.mlrg.olcut.provenance.Provenance> runProvenance) Trains a predictive model using the examples in the given data set.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.tribuo.Trainer

train

Constructor Detail

KernelSVMTrainer

public KernelSVMTrainer(Kernel kernel,
                        double lambda,
                        int epochs,
                        int loggingInterval,
                        long seed)

Constructs a trainer for a kernel SVM model.

Parameters:

kernel - The kernel function to use as a similarity measure.

epochs - The number of epochs (complete passes through the training data).

lambda - l2 regulariser on the support vectors.

loggingInterval - Log the loss after this many iterations. If -1 don't log anything.

seed - A seed for the random number generator, used to shuffle the examples before each epoch.

KernelSVMTrainer

public KernelSVMTrainer(Kernel kernel,
                        double lambda,
                        int epochs,
                        long seed)

Constructs a trainer for a kernel SVM model. Sets the logging interval to 1000.

Parameters:

kernel - The kernel function to use as a similarity measure.

lambda - l2 regulariser on the support vectors.

epochs - The number of epochs (complete passes through the training data).

seed - A seed for the random number generator, used to shuffle the examples before each epoch.

Method Detail

postConfig

public void postConfig()

Used by the OLCUT configuration system, and should not be called by external code.

Specified by:

postConfig in interface com.oracle.labs.mlrg.olcut.config.Configurable

setShuffle

public void setShuffle(boolean shuffle)

Turn on or off shuffling of examples.

This isn't exposed in the constructor as it defaults to on. This method should only be used for debugging.

Parameters:

shuffle - If true shuffle the examples, if false leave them in their current order.

train

public KernelSVMModel train(Dataset<Label> examples,
                            Map<String,com.oracle.labs.mlrg.olcut.provenance.Provenance> runProvenance)

Description copied from interface: Trainer

Trains a predictive model using the examples in the given data set.

Specified by:

train in interface Trainer<Label>

Parameters:

examples - the data set containing the examples.

runProvenance - Training run specific provenance (e.g., fold number).

Returns:

a predictive model that can be used to generate predictions for new examples.

getInvocationCount

public int getInvocationCount()

Description copied from interface: Trainer

The number of times this trainer instance has had it's train method invoked.

This is used to determine how many times the trainer's RNG has been accessed to ensure replicability in the random number stream.

Specified by:

getInvocationCount in interface Trainer<Label>

Returns:

The number of train invocations.

toString

public String toString()

Overrides:

toString in class Object

getProvenance

public TrainerProvenance getProvenance()

Specified by:

getProvenance in interface com.oracle.labs.mlrg.olcut.provenance.Provenancable<TrainerProvenance>