jsat.distributions.kernels

Class DistanceMetricBasedKernel

java.lang.Object

jsat.distributions.kernels.DistanceMetricBasedKernel

All Implemented Interfaces:

Serializable, Cloneable, KernelTrick, Parameterized

Direct Known Subclasses:

GeneralRBFKernel

public abstract class DistanceMetricBasedKernel
extends Object
implements KernelTrick

This abstract class provides the means of implementing a Kernel based off some DistanceMetric. This will pre-implement most of the methods of the KernelTrick interface, including using the distance acceleration of the metric (if supported) when appropriate.

Author:

Edward Raff

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected DistanceMetric	d the distance metric to use for the Kernel

Constructor Summary

Constructors

Constructor and Description
DistanceMetricBasedKernel(DistanceMetric d) Creates a new distance based kerenel

Method Summary

Modifier and Type	Method and Description
void	addToCache(Vec newVec, List<Double> cache) Appends the new cache values for the given vector to the list of cache values.
abstract KernelTrick	clone()
double	evalSum(List<? extends Vec> finalSet, List<Double> cache, double[] alpha, Vec y, int start, int end) Performs an efficient summation of kernel products of the form ∑ αi k(xi, y) where x are the final set of vectors, and α the associated scalar multipliers
double	evalSum(List<? extends Vec> finalSet, List<Double> cache, double[] alpha, Vec y, List<Double> qi, int start, int end) Performs an efficient summation of kernel products of the form ∑ αi k(xi, y) where x are the final set of vectors, and α the associated scalar multipliers
List<Double>	getAccelerationCache(List<? extends Vec> trainingSet) Creates a new list cache values from a given list of training set vectors.
Parameter	getParameter(String paramName) Returns the parameter with the given name.
List<Parameter>	getParameters() Returns the list of parameters that can be altered for this learner.
List<Double>	getQueryInfo(Vec q) Pre computes query information that would have be generated if the query was a member of the original list of vectors when calling KernelTrick.getAccelerationCache(java.util.List) .
boolean	supportsAcceleration() Indicates if this kernel supports building an acceleration cache using the KernelTrick.getAccelerationCache(List) and associated cache accelerated methods.

Methods inherited from class java.lang.Object

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

Methods inherited from interface jsat.distributions.kernels.KernelTrick

eval, eval, eval, normalized, toString

Field Detail

d

protected DistanceMetric d

the distance metric to use for the Kernel

Constructor Detail

DistanceMetricBasedKernel

public DistanceMetricBasedKernel(DistanceMetric d)

Creates a new distance based kerenel

Parameters:

d - the distance metric to use

Method Detail

clone

public abstract KernelTrick clone()

Specified by:

clone in interface KernelTrick

Overrides:

clone in class Object

supportsAcceleration

public boolean supportsAcceleration()

Description copied from interface: KernelTrick

Indicates if this kernel supports building an acceleration cache using the KernelTrick.getAccelerationCache(List) and associated cache accelerated methods. By default this method will return false. If true, then a cache can be obtained from this matrix and used in conjunction with KernelTrick.eval(int, Vec, List, List, List) and KernelTrick.eval(int, int, List, List) to perform kernel products.

Specified by:

supportsAcceleration in interface KernelTrick

Returns:

true if cache acceleration is supported for this kernel, false otherwise.

getAccelerationCache

public List<Double> getAccelerationCache(List<? extends Vec> trainingSet)

Description copied from interface: KernelTrick

Creates a new list cache values from a given list of training set vectors. If this kernel does not support acceleration, null will be returned.

Specified by:

getAccelerationCache in interface KernelTrick

Parameters:

trainingSet - the list of training set vectors

Returns:

a list of cache values that may be used by this kernel

getQueryInfo

public List<Double> getQueryInfo(Vec q)

Description copied from interface: KernelTrick

Pre computes query information that would have be generated if the query was a member of the original list of vectors when calling KernelTrick.getAccelerationCache(java.util.List) . This can then be used if a large number of kernel computations are going to be done against points in the original set for a point that is outside the original space.

If this kernel does not support acceleration, null will be returned.

Specified by:

getQueryInfo in interface KernelTrick

Parameters:

q - the query point to generate cache information for

Returns:

the cache information for the query point

addToCache

public void addToCache(Vec newVec,
                       List<Double> cache)

Description copied from interface: KernelTrick

Appends the new cache values for the given vector to the list of cache values. This method is present for online style kernel learning algorithms, where the set of vectors is not known in advance. When a vector is added to the set of kernel vectors, its cache values can be added using this method.

The results of calling this sequentially on a lit of vectors starting with an empty double list is equivalent to getting the results from calling KernelTrick.getAccelerationCache(java.util.List)

If this kernel does not support acceleration, this method call will function as a nop.

Specified by:

addToCache in interface KernelTrick

Parameters:

newVec - the new vector to add to the cache values

cache - the original list of cache values to add to

evalSum

public double evalSum(List<? extends Vec> finalSet,
                      List<Double> cache,
                      double[] alpha,
                      Vec y,
                      int start,
                      int end)

Description copied from interface: KernelTrick

Performs an efficient summation of kernel products of the form
∑ α_i k(x_i, y)
where x are the final set of vectors, and α the associated scalar multipliers

Specified by:

evalSum in interface KernelTrick

Parameters:

finalSet - the final set of vectors

cache - the cache associated with the final set of vectors

alpha - the coefficients associated with each vector

y - the vector to perform the summed kernel products against

start - the starting index (inclusive) to sum from

end - the ending index (exclusive) to sum from

Returns:

the sum of the multiplied kernel products

evalSum

public double evalSum(List<? extends Vec> finalSet,
                      List<Double> cache,
                      double[] alpha,
                      Vec y,
                      List<Double> qi,
                      int start,
                      int end)

Description copied from interface: KernelTrick

Performs an efficient summation of kernel products of the form
∑ α_i k(x_i, y)
where x are the final set of vectors, and α the associated scalar multipliers

Specified by:

evalSum in interface KernelTrick

Parameters:

finalSet - the final set of vectors

cache - the cache associated with the final set of vectors

alpha - the coefficients associated with each vector

y - the vector to perform the summed kernel products against

qi - the query information about y

start - the starting index (inclusive) to sum from

end - the ending index (exclusive) to sum from

Returns:

the sum of the multiplied kernel products

getParameters

public List<Parameter> getParameters()

Description copied from interface: Parameterized

Returns the list of parameters that can be altered for this learner.

Specified by:

getParameters in interface Parameterized

Returns:

the list of parameters that can be altered for this learner.

getParameter

public Parameter getParameter(String paramName)

Description copied from interface: Parameterized

Returns the parameter with the given name. Two different strings may map to a single Parameter object. An ASCII only string, and a Unicode style string.

Specified by:

getParameter in interface Parameterized

Parameters:

paramName - the name of the parameter to obtain

Returns:

the Parameter in question, or null if no such named Parameter exists.