gov.sandia.cognition.graph.inference

Class CostSpeedupEnergyFunction<LabelType,NodeNameType>

java.lang.Object

gov.sandia.cognition.graph.inference.CostSpeedupEnergyFunction<LabelType,NodeNameType>

Type Parameters:

LabelType - The labels that can be assigned to nodes

NodeNameType - The type used to name nodes

All Implemented Interfaces:

EnergyFunction<LabelType>, NodeNameAwareEnergyFunction<LabelType,NodeNameType>

public class CostSpeedupEnergyFunction<LabelType,NodeNameType>
extends java.lang.Object
implements NodeNameAwareEnergyFunction<LabelType,NodeNameType>

This class trades memory usage (to store all of the costs) for compute time. We've found that sometimes one of the slowest parts of belief propagation is the multiple log operations, and this class eliminates a significant number of those. It appears that it depends on the size of the graph if the memory overhead outweighs the benefits of the less computations.

Author:

jdwendt

Constructor Summary

Constructors

Constructor and Description
CostSpeedupEnergyFunction(NodeNameAwareEnergyFunction<LabelType,NodeNameType> wrapme) Initializes this with the wrapped function and empty values for the pairwise costs (which are only computed and stored as needed).

Method Summary

Modifier and Type	Method and Description
void	clearStoredCosts() Clears the pre-computed costs that were stored to keep from calling log and potential each time.
java.util.Map<LabelType,java.lang.Double>	getBeliefs(NodeNameType node, EnergyFunctionSolver<LabelType> bp) Get the probabilities for each label for the input node as produced by the input belief propagation run.
Pair<java.lang.Integer,java.lang.Integer>	getEdge(int i) Returns the indices for the two endpoints in the specified path.
double	getPairwiseCost(int edgeId, LabelType ilabel, LabelType jlabel) This is the -log(getPairwisePotential(.)).
double	getPairwisePotential(int edgeId, LabelType ilabel, LabelType jlabel) Returns the pairwise cost of node i being assigned label_i and node j being assigned label_j.
java.util.Collection<LabelType>	getPossibleLabels(int nodeId) Returns the set of labels that this message passer supports
double	getUnaryCost(int i, LabelType label) This is the -log(getUnaryPotential(.)).
double	getUnaryPotential(int i, LabelType label) Returns the unary cost for node i having the input label.
int	numEdges() Returns the number of paths that messages should be passed down.
int	numNodes() Returns the number of nodes in the energy function.
void	setLabel(NodeNameType node, LabelType label) Set the label for the input node

Methods inherited from class java.lang.Object

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

Constructor Detail

CostSpeedupEnergyFunction

public CostSpeedupEnergyFunction(NodeNameAwareEnergyFunction<LabelType,NodeNameType> wrapme)

Initializes this with the wrapped function and empty values for the pairwise costs (which are only computed and stored as needed).

Parameters:

wrapme - The function to wrap with this one

Method Detail

clearStoredCosts

public void clearStoredCosts()

Clears the pre-computed costs that were stored to keep from calling log and potential each time. Necessary for if we want to re-use the function without re-initializing memory.

setLabel

public void setLabel(NodeNameType node,
                     LabelType label)

Description copied from interface: NodeNameAwareEnergyFunction

Set the label for the input node

Specified by:

setLabel in interface NodeNameAwareEnergyFunction<LabelType,NodeNameType>

See Also:

NodeNameAwareEnergyFunction.setLabel(java.lang.Object, java.lang.Object)

getBeliefs

public java.util.Map<LabelType,java.lang.Double> getBeliefs(NodeNameType node,
                                                            EnergyFunctionSolver<LabelType> bp)

Description copied from interface: NodeNameAwareEnergyFunction

Get the probabilities for each label for the input node as produced by the input belief propagation run.

Specified by:

getBeliefs in interface NodeNameAwareEnergyFunction<LabelType,NodeNameType>

Returns:

See Also:

NodeNameAwareEnergyFunction#getBeliefs(java.lang.Object, gov.sandia.cognition.graph.inference.BeliefPropagation)

getPossibleLabels

public java.util.Collection<LabelType> getPossibleLabels(int nodeId)

Description copied from interface: EnergyFunction

Returns the set of labels that this message passer supports

Specified by:

getPossibleLabels in interface EnergyFunction<LabelType>

Parameters:

nodeId - The node whose labels is wanted

Returns:

the set of labels that this message passer supports

See Also:

EnergyFunction.getPossibleLabels(int)

numEdges

public int numEdges()

Description copied from interface: EnergyFunction

Returns the number of paths that messages should be passed down. In conjunction with the EnergyFunction.getEdge(int) method, all paths can be retrieved.

Specified by:

numEdges in interface EnergyFunction<LabelType>

Returns:

the number of paths that messages can be passed through

See Also:

EnergyFunction.numEdges()

numNodes

public int numNodes()

Description copied from interface: EnergyFunction

Returns the number of nodes in the energy function.

Specified by:

numNodes in interface EnergyFunction<LabelType>

Returns:

the number of nodes in the energy function

See Also:

EnergyFunction.numNodes()

getEdge

public Pair<java.lang.Integer,java.lang.Integer> getEdge(int i)

Description copied from interface: EnergyFunction

Returns the indices for the two endpoints in the specified path. The path ID should be 0-indexed and all paths from 0 through ( EnergyFunction.numEdges() - 1) should return a non-null value. All path IDs outside that range should throw an Exception.

Specified by:

getEdge in interface EnergyFunction<LabelType>

Parameters:

i - The path ID (should be in [0 ... EnergyFunction.numEdges()) ).

Returns:

The two endpoints' IDs (to be used for #getUnaryCost(int) and #getPairwisePotential(int, int, Object, Object))

See Also:

EnergyFunction.getEdge(int)

getUnaryPotential

public double getUnaryPotential(int i,
                                LabelType label)

Description copied from interface: EnergyFunction

Returns the unary cost for node i having the input label. i must be a valid node id returned from EnergyFunction.getEdge(int). If not, an exception should be thrown.

Specified by:

getUnaryPotential in interface EnergyFunction<LabelType>

Parameters:

i - The index of the node whose unary cost should be returned

label - The label that could be applied to the node

Returns:

The unary cost of node i being assigned the input label

See Also:

EnergyFunction.getUnaryPotential(int, java.lang.Object)

getPairwisePotential

public double getPairwisePotential(int edgeId,
                                   LabelType ilabel,
                                   LabelType jlabel)

Description copied from interface: EnergyFunction

Returns the pairwise cost of node i being assigned label_i and node j being assigned label_j. NOTE: i and j must be the two endpoints returned by EnergyFunction.getEdge(int) in the ordere specified by the returned pair (i = getFirst, j = getSecond). If not, an exception should be thrown.

Specified by:

getPairwisePotential in interface EnergyFunction<LabelType>

Parameters:

edgeId - The id for the edge being requested

ilabel - The label being (possibly) assigned to node i

jlabel - The label being (possibly) assigned to node j

Returns:

the pairwise cost of node i being assigned label_i and node j being assigned label_j

See Also:

EnergyFunction.getPairwisePotential(int, java.lang.Object, java.lang.Object)

getUnaryCost

public double getUnaryCost(int i,
                           LabelType label)

Description copied from interface: EnergyFunction

This is the -log(getUnaryPotential(.)).

Specified by:

getUnaryCost in interface EnergyFunction<LabelType>

Returns:

See Also:

EnergyFunction.getUnaryCost(int, java.lang.Object)

getPairwiseCost

public double getPairwiseCost(int edgeId,
                              LabelType ilabel,
                              LabelType jlabel)

Description copied from interface: EnergyFunction

This is the -log(getPairwisePotential(.)).

Specified by:

getPairwiseCost in interface EnergyFunction<LabelType>

Returns:

See Also:

EnergyFunction.getPairwiseCost(int, java.lang.Object, java.lang.Object)