/**
* Creates a trace for the given weight with the given eligibility value
*
* @param weight the VFA weight
* @param eligibilityValue the eligibility to assign to it.
*/
public EligibilityTraceVector(FunctionWeight weight, double eligibilityValue) {
this.weight = weight;
this.eligibilityValue = eligibilityValue;
this.initialWeightValue = weight.weightValue();
}
@Override
public EpisodeAnalysis runLearningEpisodeFrom(State initialState) {
EpisodeAnalysis ea = new EpisodeAnalysis(initialState);
maxWeightChangeInLastEpisode = 0.;
State curState = initialState;
eStepCounter = 0;
Map<Integer, EligibilityTraceVector> traces =
new HashMap<Integer, GradientDescentSarsaLam.EligibilityTraceVector>();
GroundedAction action = this.learningPolicy.getAction(curState);
List<ActionApproximationResult> allCurApproxResults = this.getAllActionApproximations(curState);
ActionApproximationResult curApprox =
ActionApproximationResult.extractApproximationForAction(allCurApproxResults, action);
while (!tf.isTerminal(curState) && eStepCounter < maxEpisodeSize) {
WeightGradient gradient = this.vfa.getWeightGradient(curApprox.approximationResult);
State nextState = action.executeIn(curState);
GroundedAction nextAction = this.learningPolicy.getAction(nextState);
List<ActionApproximationResult> allNextApproxResults =
this.getAllActionApproximations(nextState);
ActionApproximationResult nextApprox =
ActionApproximationResult.extractApproximationForAction(allNextApproxResults, nextAction);
double nextQV = nextApprox.approximationResult.predictedValue;
if (tf.isTerminal(nextState)) {
nextQV = 0.;
}
// manage option specifics
double r = 0.;
double discount = this.gamma;
if (action.action.isPrimitive()) {
r = rf.reward(curState, action, nextState);
eStepCounter++;
ea.recordTransitionTo(nextState, action, r);
} else {
Option o = (Option) action.action;
r = o.getLastCumulativeReward();
int n = o.getLastNumSteps();
discount = Math.pow(this.gamma, n);
eStepCounter += n;
if (this.shouldDecomposeOptions) {
ea.appendAndMergeEpisodeAnalysis(o.getLastExecutionResults());
} else {
ea.recordTransitionTo(nextState, action, r);
}
}
// delta
double delta = r + (discount * nextQV) - curApprox.approximationResult.predictedValue;
if (useReplacingTraces) {
// then first clear traces of unselected action and reset the trace for the selected one
for (ActionApproximationResult aar : allCurApproxResults) {
if (!aar.ga.equals(action)) { // clear unselected action trace
for (FunctionWeight fw : aar.approximationResult.functionWeights) {
traces.remove(fw.weightId());
}
} else { // reset trace of selected action
for (FunctionWeight fw : aar.approximationResult.functionWeights) {
EligibilityTraceVector storedTrace = traces.get(fw.weightId());
if (storedTrace != null) {
storedTrace.eligibilityValue = 0.;
}
}
}
}
}
// update all traces
Set<Integer> deletedSet = new HashSet<Integer>();
for (EligibilityTraceVector et : traces.values()) {
int weightId = et.weight.weightId();
et.eligibilityValue += gradient.getPartialDerivative(weightId);
double newWeight =
et.weight.weightValue() + this.learningRate * delta * et.eligibilityValue;
et.weight.setWeight(newWeight);
double deltaW = Math.abs(et.initialWeightValue - newWeight);
if (deltaW > maxWeightChangeInLastEpisode) {
maxWeightChangeInLastEpisode = deltaW;
}
et.eligibilityValue *= this.lambda * discount;
if (et.eligibilityValue < this.minEligibityForUpdate) {
deletedSet.add(weightId);
}
}
// add new traces if need be
for (FunctionWeight fw : curApprox.approximationResult.functionWeights) {
int weightId = fw.weightId();
if (!traces.containsKey(fw)) {
// then it's new and we need to add it
EligibilityTraceVector et =
new EligibilityTraceVector(fw, gradient.getPartialDerivative(weightId));
double newWeight = fw.weightValue() + this.learningRate * delta * et.eligibilityValue;
fw.setWeight(newWeight);
double deltaW = Math.abs(et.initialWeightValue - newWeight);
if (deltaW > maxWeightChangeInLastEpisode) {
maxWeightChangeInLastEpisode = deltaW;
}
et.eligibilityValue *= this.lambda * discount;
if (et.eligibilityValue >= this.minEligibityForUpdate) {
traces.put(weightId, et);
}
}
}
// delete any traces
for (Integer t : deletedSet) {
traces.remove(t);
}
// move on
curState = nextState;
action = nextAction;
curApprox = nextApprox;
allCurApproxResults = allNextApproxResults;
}
if (episodeHistory.size() >= numEpisodesToStore) {
episodeHistory.poll();
episodeHistory.offer(ea);
}
return ea;
}
