public Pair <MDPUtilityFunction <STATE_TYPE>, Double> valueIterateOnce(
double gamma, MDPUtilityFunction <STATE_TYPE> presentUtilityFunction)
{
double maxUtilityGrowth = 0.0;
MDPUtilityFunction <STATE_TYPE> newUtilityFunction = new MDPUtilityFunction <STATE_TYPE>();
foreach (STATE_TYPE s in nonFinalstates)
{
// double utility = rewardFunction.getRewardFor(s)
// + (gamma * highestUtilityTransition.getSecond());
double utility = valueIterateOnceForGivenState(gamma,
presentUtilityFunction, s);
double differenceInUtility = Math.Abs(utility
- presentUtilityFunction.getUtility(s));
if (differenceInUtility > maxUtilityGrowth)
{
maxUtilityGrowth = differenceInUtility;
}
newUtilityFunction.setUtility(s, utility);
foreach (STATE_TYPE state in terminalStates)
{
newUtilityFunction.setUtility(state, presentUtilityFunction
.getUtility(state));
}
}
return(new Pair <MDPUtilityFunction <STATE_TYPE>, Double>(
newUtilityFunction, maxUtilityGrowth));
}
public MDPUtilityFunction <STATE_TYPE> valueIteration(double gamma,
double error, double delta)
{
MDPUtilityFunction <STATE_TYPE> U = initialUtilityFunction();
MDPUtilityFunction <STATE_TYPE> U_dash = initialUtilityFunction();
double delta_max = (error * gamma) / (1 - gamma);
do
{
U = U_dash.copy();
// System.Console.WriteLine(U);
delta = 0.0;
foreach (STATE_TYPE s in nonFinalstates)
{
Pair <ACTION_TYPE, Double> highestUtilityTransition = transitionModel
.getTransitionWithMaximumExpectedUtility(s, U);
double utility = rewardFunction.getRewardFor(s)
+ (gamma * highestUtilityTransition.getSecond());
U_dash.setUtility(s, utility);
if ((Math.Abs(U_dash.getUtility(s) - U.getUtility(s))) > delta)
{
delta = Math.Abs(U_dash.getUtility(s) - U.getUtility(s));
}
}
} while (delta < delta_max);
return(U);
}
public MDPUtilityFunction <STATE_TYPE> asUtilityFunction()
{
MDPUtilityFunction <STATE_TYPE> uf = new MDPUtilityFunction <STATE_TYPE>();
foreach (STATE_TYPE state in stateToReward.Keys)
{
uf.setUtility(state, getRewardFor(state));
}
return(uf);
}
public MDPUtilityFunction <STATE_TYPE> copy()
{
MDPUtilityFunction <STATE_TYPE> other = new MDPUtilityFunction <STATE_TYPE>();
foreach (STATE_TYPE state in hash.Keys)
{
other.setUtility(state, hash[state]);
}
return(other);
}
private MDPUtilityFunction <STATE_TYPE> valueIterateOnceWith(double gamma,
MDPPolicy <STATE_TYPE, ACTION_TYPE> pi,
MDPUtilityFunction <STATE_TYPE> U)
{
MDPUtilityFunction <STATE_TYPE> U_dash = U.copy();
foreach (STATE_TYPE s in nonFinalstates)
{
Pair <ACTION_TYPE, Double> highestPolicyTransition = transitionModel
.getTransitionWithMaximumExpectedUtilityUsingPolicy(pi, s,
U);
double utility = rewardFunction.getRewardFor(s)
+ (gamma * highestPolicyTransition.getSecond());
U_dash.setUtility(s, utility);
}
// System.Console.WriteLine("ValueIterationOnce before " + U);
// System.Console.WriteLine("ValueIterationOnce after " + U_dash);
return(U_dash);
}
