burlap.behavior.policy

Class CachedPolicy

java.lang.Object

burlap.behavior.policy.Policy

burlap.behavior.policy.CachedPolicy

public class CachedPolicy
extends Policy

This class can be used to lazily cache the policy of a source policy. This is useful when the source policy may require some degree of computation and you'd like to store the results of that computation to memory so that it does not have be recomputed for states that have their policy queried multiple times.

Author:

James MacGlashan.

Nested Class Summary

Nested classes/interfaces inherited from class burlap.behavior.policy.Policy

Policy.ActionProb, Policy.GroundedAnnotatedAction, Policy.PolicyUndefinedException

Field Summary

Fields

Modifier and Type	Field and Description
protected java.util.Map<HashableState,java.util.List<Policy.ActionProb>>	actionSelection The cached action selection probabilities
protected HashableStateFactory	hashingFactory The hashing factory to use for indexing states
protected Policy	sourcePolicy The source policy that gets cached

Fields inherited from class burlap.behavior.policy.Policy

annotateOptionDecomposition, evaluateDecomposesOptions

Constructor Summary

Constructors

Constructor and Description
CachedPolicy(HashableStateFactory hashingFactory, Policy sourcePolicy) Initializes
CachedPolicy(HashableStateFactory hashingFactory, Policy sourcePolicy, int cacheCapacity) Initializes

Method Summary

Methods

Modifier and Type	Method and Description
AbstractGroundedAction	getAction(State s) This method will return an action sampled by the policy for the given state.
java.util.List<Policy.ActionProb>	getActionDistributionForState(State s) This method will return action probability distribution defined by the policy.
boolean	isDefinedFor(State s) Specifies whether this policy is defined for the input state.
boolean	isStochastic() Indicates whether the policy is stochastic or deterministic.

Methods inherited from class burlap.behavior.policy.Policy

evaluateBehavior, evaluateBehavior, evaluateBehavior, evaluateBehavior, evaluateBehavior, evaluateMethodsShouldAnnotateOptionDecomposition, evaluateMethodsShouldDecomposeOption, followAndRecordPolicy, followAndRecordPolicy, getDeterministicPolicy, getProbOfAction, getProbOfActionGivenDistribution, getProbOfActionGivenDistribution, sampleFromActionDistribution

Methods inherited from class java.lang.Object

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

Field Detail

hashingFactory

protected HashableStateFactory hashingFactory

The hashing factory to use for indexing states

actionSelection

protected java.util.Map<HashableState,java.util.List<Policy.ActionProb>> actionSelection

The cached action selection probabilities

sourcePolicy

protected Policy sourcePolicy

The source policy that gets cached

Constructor Detail

CachedPolicy

public CachedPolicy(HashableStateFactory hashingFactory,
            Policy sourcePolicy)

Initializes

Parameters:

hashingFactory - the HashableStateFactory to use for indexing states

sourcePolicy - the source policy that will be lazily cached.

CachedPolicy

public CachedPolicy(HashableStateFactory hashingFactory,
            Policy sourcePolicy,
            int cacheCapacity)

Initializes

Parameters:

hashingFactory - the HashableStateFactory to use for indexing states

sourcePolicy - the source policy that will be lazily cached.

cacheCapacity - the initial memory capacity to be set aside for the policy cache

Method Detail

getAction

public AbstractGroundedAction getAction(State s)

Description copied from class: Policy

This method will return an action sampled by the policy for the given state. If the defined policy is stochastic, then multiple calls to this method for the same state may return different actions. The sampling should be with respect to defined action distribution that is returned by getActionDistributionForState

Specified by:

getAction in class Policy

Parameters:

s - the state for which an action should be returned

Returns:

a sample action from the action distribution; null if the policy is undefined for s

getActionDistributionForState

public java.util.List<Policy.ActionProb> getActionDistributionForState(State s)

Description copied from class: Policy

This method will return action probability distribution defined by the policy. The action distribution is represented by a list of ActionProb objects, each which specifies a grounded action and a probability of that grounded action being taken. The returned list does not have to include actions with probability 0.

Specified by:

getActionDistributionForState in class Policy

Parameters:

s - the state for which an action distribution should be returned

Returns:

a list of possible actions taken by the policy and their probability.

isStochastic

public boolean isStochastic()

Description copied from class: Policy

Indicates whether the policy is stochastic or deterministic.

Specified by:

isStochastic in class Policy

Returns:

true when the policy is stochastic; false when it is deterministic.

isDefinedFor

public boolean isDefinedFor(State s)

Description copied from class: Policy

Specifies whether this policy is defined for the input state.

Specified by:

isDefinedFor in class Policy

Parameters:

s - the input state to test for whether this policy is defined

Returns:

true if this policy is defined for State s, false otherwise.