burlap.mdp.core.state

Interface State

All Known Subinterfaces:

BeliefState, DenseBeliefVector, EnumerableBeliefState, MutableOOState, MutableState, ObjectInstance, OOState, StateDomain

All Known Implementing Classes:

BlockDudeAgent, BlockDudeCell, BlockDudeMap, BlockDudeState, BlocksWorldBlock, BlocksWorldState, CartPoleFullState, CartPoleState, DeepOOState, FrostbiteAgent, FrostbiteIgloo, FrostbitePlatform, FrostbiteState, GenericOOState, GGAgent, GGGoal, GGWall, GGWall.GGHorizontalWall, GGWall.GGVerticalWall, GraphStateNode, GridAgent, GridLocation, GridWorldState, HistoryState, InvertedPendulumState, LLAgent, LLBlock, LLBlock.LLObstacle, LLBlock.LLPad, LLState, MCState, NFGameState, NullState, RLGlueState, TabularBeliefState, TigerObservation, TigerState

public interface State

A State instance is used to define the state of an environment or an observation from the environment. Creating a state requires implementing three methods to ensure compatibility with all BURLAP tools. First, the variableKeys() method should return a list of objects that represent the possible keys that are used to reference state variables in your state. In general, a state variable is any value that when changed alters the identification of the state. That is, two states with different state variables would not be equal and transition dynamics and reward functions from them may be different as a result.

Next the get(Object) method should accept any argument that is listed in the variableKeys() list and should return the value of that variable. You do *not* have to guarantee that changes the client makes to the returned value will affect the state.

Finally, the copy() method must be implemented so that a copy of this state can be created. State copy operations are often performed when generating state transitions, or when a copy of the information needs to be held by some other data structure. The copy may be a shallow copy or deep copy and is domain/implementation specific. For clarity, the State implementation may indicate its copy mode with the DeepCopyState or ShallowCopyState annotations. If it is a shallow copy, you should not *directly* modify any fields of a copied state without copying the fields first, or it could contaminate the state from which the copy was made. Alternatively, use the MutableState.set(Object, Object) method to modify ShallowCopyState copied states, which for ShallowCopyState instances should perform a safe copy-on-write operation.

Author:

James MacGlashan

Method Summary

Modifier and Type	Method and Description
State	copy() Returns a copy of this state suitable for creating state transitions.
java.lang.Object	get(java.lang.Object variableKey) Returns the value for the given variable key.
java.util.List<java.lang.Object>	variableKeys() Returns the list of state variable keys.

Method Detail

variableKeys

java.util.List<java.lang.Object> variableKeys()

Returns the list of state variable keys.

Returns:

the list of state variable keys.

get

java.lang.Object get(java.lang.Object variableKey)

Returns the value for the given variable key. Changes to the returned value are not guaranteed to modify the state.

Parameters:

variableKey - the variable key

Returns:

the value for the given variable key

copy

State copy()

Returns a copy of this state suitable for creating state transitions. This copy may be a shallow copy or deep copy and is domain specific. The State implementation may indicate its copy level with the DeepCopyState or ShallowCopyState annotations. If it is a shallow copy, you should not *directly* modify any fields of a copied state without copying the fields first, or it could contaminate the state from which the copy was made. Alternatively, use the MutableState.set(Object, Object) method to modify ShallowCopyState copied states, which for ShallowCopyState instances should perform a safe copy-on-write operation.

Returns:

a copy of this state.