burlap.domain.singleagent.gridworld

Class GridWorldTerminalFunction

java.lang.Object

burlap.domain.singleagent.gridworld.GridWorldTerminalFunction

All Implemented Interfaces:

TerminalFunction

public class GridWorldTerminalFunction
extends java.lang.Object
implements TerminalFunction

This class is used for setting a terminal function for GridWorlds that is based on the location of the agent in the world. An alternative approch would be to use location objects and the atLocation propositional function to specify terminal states, but this approach may be simpler to define or when terminal states are defined independent of location objects.

The set of terminal positions is defined either in the constructor or with subsequent calls to the markAsTerminalPosition(int, int) method. Terminal positions may also be removed with the unmarkTerminalPosition(int, int) and unmarkAllTerminalPositions() methods.

Author:

James MacGlashan

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	GridWorldTerminalFunction.IntPair A pair class for two ints.

Field Summary

Fields

Modifier and Type	Field and Description
protected java.util.Set<GridWorldTerminalFunction.IntPair>	terminalPositions The set of positions marked as terminal positions.

Constructor Summary

Constructors

Constructor and Description
GridWorldTerminalFunction() Initializes without any terminal positions specified.
GridWorldTerminalFunction(GridWorldTerminalFunction.IntPair... terminalPositions) Initializes with a list of terminal positions specified by a sequence of GridWorldTerminalFunction.IntPair objects.
GridWorldTerminalFunction(int x, int y) Initializes with a terminal position at the specified agent x and y locaiton.

Method Summary

Modifier and Type	Method and Description
boolean	isTerminal(State s)
boolean	isTerminalPosition(int x, int y) Returns true if a position is marked as a terminal position; false otherwise.
void	markAsTerminalPosition(int x, int y) Marks a position as a terminal position for the agent.
void	unmarkAllTerminalPositions() Unmarks all agent positions as terminal positions.
void	unmarkTerminalPosition(int x, int y) Unmarks an agent position as a terminal position.

Methods inherited from class java.lang.Object

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

Field Detail

terminalPositions

protected java.util.Set<GridWorldTerminalFunction.IntPair> terminalPositions

The set of positions marked as terminal positions.

Constructor Detail

GridWorldTerminalFunction

public GridWorldTerminalFunction()

Initializes without any terminal positions specified.

GridWorldTerminalFunction

public GridWorldTerminalFunction(int x,
                                 int y)

Initializes with a terminal position at the specified agent x and y locaiton.

Parameters:

x - the x location of the agent

y - the y location of the agent

GridWorldTerminalFunction

public GridWorldTerminalFunction(GridWorldTerminalFunction.IntPair... terminalPositions)

Initializes with a list of terminal positions specified by a sequence of GridWorldTerminalFunction.IntPair objects.

Parameters:

terminalPositions - the agent positions that are terminal states, specified with GridWorldTerminalFunction.IntPair objects.

Method Detail

markAsTerminalPosition

public void markAsTerminalPosition(int x,
                                   int y)

Marks a position as a terminal position for the agent.

Parameters:

x - the x location of the agent.

y - the y location of the agent.

unmarkTerminalPosition

public void unmarkTerminalPosition(int x,
                                   int y)

Unmarks an agent position as a terminal position.

Parameters:

x - the x location of the agent.

y - the y location of the agent.

unmarkAllTerminalPositions

public void unmarkAllTerminalPositions()

Unmarks all agent positions as terminal positions. That is, no position will be considered a terminal position.

isTerminalPosition

public boolean isTerminalPosition(int x,
                                  int y)

Returns true if a position is marked as a terminal position; false otherwise.

Parameters:

x - the x location of the agent.

y - the y location of the agent.

Returns:

true if a position is marked as a terminal position; false otherwise.

isTerminal

public boolean isTerminal(State s)

Specified by:

isTerminal in interface TerminalFunction