burlap.behavior.singleagent.learning.tdmethods

Class SarsaLam

java.lang.Object

burlap.behavior.singleagent.MDPSolver

burlap.behavior.singleagent.learning.tdmethods.QLearning

burlap.behavior.singleagent.learning.tdmethods.SarsaLam

All Implemented Interfaces:

LearningAgent, MDPSolverInterface, Planner, QFunction, QProvider, ValueFunction

public class SarsaLam
extends QLearning

Tabular SARSA(\lambda) implementation [1]. This implementation will work correctly with options [2]. The implementation can either be used for learning or planning, the latter of which is performed by running many learning episodes in succession in a SimulatedEnvironment. If you are going to use this algorithm for planning, call the QLearning.initializeForPlanning(int) method before calling QLearning.planFromState(State). The number of episodes used for planning can be determined by a threshold maximum number of episodes, or by a maximum change in the Q-function threshold.

By default, this agent will use an epsilon-greedy policy with epsilon=0.1. You can change the learning policy to anything with the QLearning.setLearningPolicy(burlap.behavior.policy.Policy) policy.

If you want to use a custom learning rate decay schedule rather than a constant learning rate, use the QLearning.setLearningRateFunction(burlap.behavior.learningrate.LearningRate).

Author:

James MacGlashan

1. Rummery, Gavin A., and Mahesan Niranjan. On-line Q-learning using connectionist systems. University of Cambridge, Department of Engineering, 1994.

2. Sutton, Richard S., Doina Precup, and Satinder Singh. "Between MDPs and semi-MDPs: A framework for temporal abstraction in reinforcement learning." Artificial intelligence 112.1 (1999): 181-211.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	SarsaLam.EligibilityTrace A data structure for maintaining eligibility trace values

Nested classes/interfaces inherited from interface burlap.behavior.valuefunction.QProvider

QProvider.Helper

Field Summary

Fields

Modifier and Type	Field and Description
protected double	lambda the strength of eligibility traces (0 for one step, 1 for full propagation)

Fields inherited from class burlap.behavior.singleagent.learning.tdmethods.QLearning

eStepCounter, learningPolicy, learningRate, maxEpisodeSize, maxQChangeForPlanningTermination, maxQChangeInLastEpisode, numEpisodesForPlanning, qFunction, qInitFunction, shouldDecomposeOptions, totalNumberOfSteps

Fields inherited from class burlap.behavior.singleagent.MDPSolver

actionTypes, debugCode, domain, gamma, hashingFactory, model, usingOptionModel

Constructor Summary

Constructors

Constructor and Description
SarsaLam(SADomain domain, double gamma, HashableStateFactory hashingFactory, double qInit, double learningRate, double lambda) Initializes SARSA(\lambda) with 0.1 epsilon greedy policy, the same Q-value initialization everywhere, and places no limit on the number of steps the agent can take in an episode.
SarsaLam(SADomain domain, double gamma, HashableStateFactory hashingFactory, double qInit, double learningRate, int maxEpisodeSize, double lambda) Initializes SARSA(\lambda) with 0.1 epsilon greedy policy, the same Q-value initialization everywhere.
SarsaLam(SADomain domain, double gamma, HashableStateFactory hashingFactory, double qInit, double learningRate, Policy learningPolicy, int maxEpisodeSize, double lambda) Initializes SARSA(\lambda) with the same Q-value initialization everywhere.
SarsaLam(SADomain domain, double gamma, HashableStateFactory hashingFactory, QFunction qInit, double learningRate, Policy learningPolicy, int maxEpisodeSize, double lambda) Initializes SARSA(\lambda).

Method Summary

Modifier and Type	Method and Description
Episode	runLearningEpisode(Environment env, int maxSteps)
protected void	sarsalamInit(double lambda)

Methods inherited from class burlap.behavior.singleagent.learning.tdmethods.QLearning

getLastNumSteps, getMaxQ, getQ, getQs, getStateNode, initializeForPlanning, loadQTable, planFromState, QLInit, qValue, qValues, resetSolver, runLearningEpisode, setLearningPolicy, setLearningRateFunction, setMaximumEpisodesForPlanning, setMaxQChangeForPlanningTerminaiton, setQInitFunction, toggleShouldDecomposeOption, value, writeQTable

Methods inherited from class burlap.behavior.singleagent.MDPSolver

addActionType, applicableActions, getActionTypes, getDebugCode, getDomain, getGamma, getHashingFactory, getModel, setActionTypes, setDebugCode, setDomain, setGamma, setHashingFactory, setModel, solverInit, stateHash, toggleDebugPrinting

Methods inherited from class java.lang.Object

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

Methods inherited from interface burlap.behavior.singleagent.MDPSolverInterface

addActionType, getActionTypes, getDebugCode, getDomain, getGamma, getHashingFactory, getModel, setActionTypes, setDebugCode, setDomain, setGamma, setHashingFactory, setModel, solverInit, toggleDebugPrinting

Field Detail

lambda

protected double lambda

the strength of eligibility traces (0 for one step, 1 for full propagation)

Constructor Detail

SarsaLam

public SarsaLam(SADomain domain,
                double gamma,
                HashableStateFactory hashingFactory,
                double qInit,
                double learningRate,
                double lambda)

Initializes SARSA(\lambda) with 0.1 epsilon greedy policy, the same Q-value initialization everywhere, and places no limit on the number of steps the agent can take in an episode. By default the agent will only save the last learning episode and a call to the QLearning.planFromState(State) method will cause the valueFunction to use only one episode for planning; this should probably be changed to a much larger value if you plan on using this algorithm as a planning algorithm.

Parameters:

domain - the domain in which to learn

gamma - the discount factor

hashingFactory - the state hashing factory to use for Q-lookups

qInit - the initial Q-value to user everywhere

learningRate - the learning rate

lambda - specifies the strength of eligibility traces (0 for one step, 1 for full propagation)

SarsaLam

public SarsaLam(SADomain domain,
                double gamma,
                HashableStateFactory hashingFactory,
                double qInit,
                double learningRate,
                int maxEpisodeSize,
                double lambda)

Initializes SARSA(\lambda) with 0.1 epsilon greedy policy, the same Q-value initialization everywhere. By default the agent will only save the last learning episode and a call to the QLearning.planFromState(State) method will cause the valueFunction to use only one episode for planning; this should probably be changed to a much larger value if you plan on using this algorithm as a planning algorithm.

Parameters:

domain - the domain in which to learn

gamma - the discount factor

hashingFactory - the state hashing factory to use for Q-lookups

qInit - the initial Q-value to user everywhere

learningRate - the learning rate

maxEpisodeSize - the maximum number of steps the agent will take in a learning episode for the agent stops trying.

lambda - specifies the strength of eligibility traces (0 for one step, 1 for full propagation)

SarsaLam

public SarsaLam(SADomain domain,
                double gamma,
                HashableStateFactory hashingFactory,
                double qInit,
                double learningRate,
                Policy learningPolicy,
                int maxEpisodeSize,
                double lambda)

Initializes SARSA(\lambda) with the same Q-value initialization everywhere. Note that if the provided policy is derived from the Q-value of this learning agent (as it should be), you may need to set the policy to point to this object after call this constructor; the constructor will not do this automatically in case it was by design to use the policy that was learned in some other domain. By default the agent will only save the last learning episode and a call to the QLearning.planFromState(State) method will cause the valueFunction to use only one episode for planning; this should probably be changed to a much larger value if you plan on using this algorithm as a planning algorithm.

Parameters:

domain - the domain in which to learn

gamma - the discount factor

hashingFactory - the state hashing factory to use for Q-lookups

qInit - the initial Q-value to user everywhere

learningRate - the learning rate

learningPolicy - the learning policy to follow during a learning episode.

maxEpisodeSize - the maximum number of steps the agent will take in a learning episode for the agent stops trying.

lambda - specifies the strength of eligibility traces (0 for one step, 1 for full propagation)

SarsaLam

public SarsaLam(SADomain domain,
                double gamma,
                HashableStateFactory hashingFactory,
                QFunction qInit,
                double learningRate,
                Policy learningPolicy,
                int maxEpisodeSize,
                double lambda)

Initializes SARSA(\lambda). Note that if the provided policy is derived from the Q-value of this learning agent (as it should be), you may need to set the policy to point to this object after call this constructor; the constructor will not do this automatically in case it was by design to use the policy that was learned in some other domain. By default the agent will only save the last learning episode and a call to the QLearning.planFromState(State) method will cause the valueFunction to use only one episode for planning; this should probably be changed to a much larger value if you plan on using this algorithm as a planning algorithm.

Parameters:

domain - the domain in which to learn

gamma - the discount factor

hashingFactory - the state hashing factory to use for Q-lookups

qInit - a QFunction object that can be used to initialize the Q-values.

learningRate - the learning rate

learningPolicy - the learning policy to follow during a learning episode.

maxEpisodeSize - the maximum number of steps the agent will take in a learning episode for the agent stops trying.

lambda - specifies the strength of eligibility traces (0 for one step, 1 for full propagation)

Method Detail

sarsalamInit

protected void sarsalamInit(double lambda)

runLearningEpisode

public Episode runLearningEpisode(Environment env,
                                  int maxSteps)

Specified by:

runLearningEpisode in interface LearningAgent

Overrides:

runLearningEpisode in class QLearning