burlap.behavior.singleagent.vfa.rbf

Class RBFFeatureDatabase

java.lang.Object

burlap.behavior.singleagent.vfa.rbf.RBFFeatureDatabase

All Implemented Interfaces:

FeatureDatabase

public class RBFFeatureDatabase
extends java.lang.Object
implements FeatureDatabase

A feature database of RBF units that can be used for linear value function approximation. This formalization for RBFs is general to any kind of state distance measure and can therefore potentially exploit the OO-MDP structure of states. However, if you plan on using Gaussian RBF units with standard Euclidean distance measures, it is recommended that you use the FVRBFFeatureDatabase instead, as it will be more computationally efficient.

Author:

Anubhav Malhotra and Daniel Fernandez and Spandan Dutta; modified by James MacGlashan

Field Summary

Fields

Modifier and Type	Field and Description
protected java.util.Map<GroundedAction,java.lang.Integer>	actionFeatureMultiplier A map for returning a multiplier to the number of RBF state features for each action.
protected boolean	hasOffset Specifies whether an offset RBF unit with a constant response value is included in the feature set.
protected int	nextActionMultiplier The next action RBF size multiplier to use for the next newly seen action.
protected int	nRbfs The number of RBF units, not including an offset unit.
protected java.util.List<RBF>	rbfs The list of RBF units in this database

Constructor Summary

Constructors

Constructor and Description
RBFFeatureDatabase(boolean hasOffset) Initializes with an empty list of RBF units.

Method Summary

Methods

Modifier and Type	Method and Description
void	addRBF(RBF rbf) Adds the specified RBF unit to the list of RBF units.
void	addRBFs(java.util.List<RBF> rbfs) Adds all of the specified RBF units to this object's list of RBF units.
RBFFeatureDatabase	copy() Returns a deep copy of this feature database.
void	freezeDatabaseState(boolean toggle) Enable or disable the database from generating new features.
LinearVFA	generateVFA(double defaultWeightValue) Creates and returns a linear VFA object over this RBF feature database.
java.util.List<ActionFeaturesQuery>	getActionFeaturesSets(State s, java.util.List<GroundedAction> actions) Returns non-zero action features for all of provided actions in state s.
protected int	getActionMultiplier(GroundedAction ga) This method returns the action multiplier for the specified grounded action.
java.util.List<StateFeature>	getStateFeatures(State s) Returns non-zero state features for a given state.
int	numberOfFeatures() Returns the number of features this database tracks.

Methods inherited from class java.lang.Object

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

Field Detail

rbfs

protected java.util.List<RBF> rbfs

The list of RBF units in this database

nRbfs

protected int nRbfs

The number of RBF units, not including an offset unit.

hasOffset

protected boolean hasOffset

Specifies whether an offset RBF unit with a constant response value is included in the feature set.

actionFeatureMultiplier

protected java.util.Map<GroundedAction,java.lang.Integer> actionFeatureMultiplier

A map for returning a multiplier to the number of RBF state features for each action. Effectively this ensures a unique feature ID for each RBF for each action.

nextActionMultiplier

protected int nextActionMultiplier

The next action RBF size multiplier to use for the next newly seen action.

Constructor Detail

RBFFeatureDatabase

public RBFFeatureDatabase(boolean hasOffset)

Initializes with an empty list of RBF units.

Parameters:

hasOffset - if true, an offset RBF unit with a constant response value is included in the feature set.

Method Detail

addRBF

public void addRBF(RBF rbf)

Adds the specified RBF unit to the list of RBF units.

Parameters:

rbf - the RBF unit to add.

addRBFs

public void addRBFs(java.util.List<RBF> rbfs)

Adds all of the specified RBF units to this object's list of RBF units.

Parameters:

rbfs - the RBF units to add.

getStateFeatures

public java.util.List<StateFeature> getStateFeatures(State s)

Description copied from interface: FeatureDatabase

Returns non-zero state features for a given state. This method should be implemented if it is to be used with algorithms that compute V-values from state features or other values that are independent of the actions.

Specified by:

getStateFeatures in interface FeatureDatabase

Parameters:

s - the state for which features should be returned

Returns:

the features for state s

getActionFeaturesSets

public java.util.List<ActionFeaturesQuery> getActionFeaturesSets(State s,
                                                        java.util.List<GroundedAction> actions)

Description copied from interface: FeatureDatabase

Returns non-zero action features for all of provided actions in state s. This method should be implemented if it is to be used with algorithms that compute Q-values from action features or other values are the dependent on the actions. Note that features for different actions should return different feature ids.

Specified by:

getActionFeaturesSets in interface FeatureDatabase

Parameters:

s - the state for which features should be returned

actions - the action set for which the action features should be returned

Returns:

returns the set set of action features for each action in actions

freezeDatabaseState

public void freezeDatabaseState(boolean toggle)

Description copied from interface: FeatureDatabase

Enable or disable the database from generating new features. This method only needs to do anything if it creates features in an online fashion. That is, if the set of possible state features is defined at construction, then this method does not need to do anything. If features are generated as needed, such as with an instance-based feature set, then when the database is told to be frozen no new instances should be created.

Specified by:

freezeDatabaseState in interface FeatureDatabase

generateVFA

public LinearVFA generateVFA(double defaultWeightValue)

Creates and returns a linear VFA object over this RBF feature database.

Parameters:

defaultWeightValue - the default feature weight value to use for all features

Returns:

a linear VFA object over this RBF feature database.

getActionMultiplier

protected int getActionMultiplier(GroundedAction ga)

This method returns the action multiplier for the specified grounded action. If the action is not stored, a new action multiplier will created, stored, and returned. If the action is parameterized a runtime exception is thrown.

Parameters:

ga - the grounded action for which the multiplier will be returned

Returns:

the action multiplier to be applied to a state feature id.

numberOfFeatures

public int numberOfFeatures()

Description copied from interface: FeatureDatabase

Returns the number of features this database tracks.

Specified by:

numberOfFeatures in interface FeatureDatabase

Returns:

the number of features this database tracks.

copy

public RBFFeatureDatabase copy()

Description copied from interface: FeatureDatabase

Returns a deep copy of this feature database. If the feature database is dynamic, then changes to one will not affect the other.

Specified by:

copy in interface FeatureDatabase

Returns:

a deep copy of this feature database