public Pair <MDPUtilityFunction <TState>, Double> ValueIterateOnce(
double gamma, MDPUtilityFunction <TState> presentUtilityFunction)
{
var maxUtilityGrowth = 0.0;
var newUtilityFunction = new MDPUtilityFunction <TState>();
foreach (TState s in nonFinalstates)
{
// TODO: figure out what to do with commented out code
// double utility = rewardFunction.getRewardFor(s)
// + (gamma * highestUtilityTransition.getSecond());
var utility = this.ValueIterateOnceForGivenState(gamma,
presentUtilityFunction, s);
var differenceInUtility = Math.Abs(utility
- presentUtilityFunction.GetUtility(s));
if (differenceInUtility > maxUtilityGrowth)
{
maxUtilityGrowth = differenceInUtility;
}
newUtilityFunction.SetUtility(s, utility);
foreach (var state in terminalStates)
{
newUtilityFunction.SetUtility(state, presentUtilityFunction
.GetUtility(state));
}
}
return(new Pair <MDPUtilityFunction <TState>, Double>(
newUtilityFunction, maxUtilityGrowth));
}
private Dictionary <TAction, Double> GetExpectedUtilityForSelectedTransitions(
IList <MDPTransition <TState, TAction> > transitions,
MDPUtilityFunction <TState> uf)
{
var actionsToUtilities = new Dictionary <TAction, double>();
foreach (var triplet in transitions)
{
var s = triplet.GetInitialState();
var action = triplet.GetAction();
var destinationState = triplet.GetDestinationState();
var probabilityOfTransition = this.GetTransitionProbability(s,
action, destinationState);
var expectedUtility = (probabilityOfTransition * uf
.GetUtility(destinationState));
if (!actionsToUtilities.ContainsKey(action))
{
actionsToUtilities[action] = expectedUtility;
}
else
{
actionsToUtilities[action] = actionsToUtilities[action] + expectedUtility;
}
}
return(actionsToUtilities);
}
