public OddmentTable <int> Create(SearchContext <object, TicTacToeState, TicTacToeMove, object, TicTacToeMove> context, int samplesForGeneration)
{
var table = new Dictionary <int, double>();
for (var i = 0; i < samplesForGeneration; i++)
{
var action = new TicTacToeMove(TicTacToeMoveGenerator.AllEmptyPositions(context.Source).RandomElementOrDefault(), context.Source.ActivePlayerID);
var newState = GameLogic.Apply(context, (TicTacToeState)context.Source.Copy(), action);
var endState = PlayoutStrategy.Playout(context, newState);
var value = EvaluationStrategy.Evaluate(context, new TreeSearchNode <TicTacToeState, TicTacToeMove>(action), endState);
if (!table.ContainsKey(action.PositionToPlace))
{
table.Add(action.PositionToPlace, 0);
}
table[action.PositionToPlace] += value;
}
var maxValue = table.Values.Max();
var minValue = table.Values.Min();
var oddmentTable = new OddmentTable <int>();
foreach (var kvPair in table)
{
var normalisedValue = Util.Normalise(kvPair.Value, minValue, maxValue);
oddmentTable.Add(kvPair.Key, normalisedValue, recalculate: false);
}
oddmentTable.Recalculate();
return(oddmentTable);
}
/// <summary>
/// Selects the best half of a collection of actions by evaluating them based on the provided search context.
/// </summary>
/// <param name="context">The current search context.</param>
/// <param name="actions">The collection of actions to filter.</param>
/// <param name="samplesPerAction">How many samples to run per action.</param>
/// <returns>Collection of actions which Count is half of the original collection, rounded up. This collection is ordered by descending value.</returns>
private List <ActionValue> SelectBestHalf(SearchContext <D, P, A, S, A> context, IReadOnlyCollection <ActionValue> actions, int samplesPerAction)
{
var clone = context.Cloner;
// Evaluate each action by running a playout for it.
foreach (var item in actions)
{
var tempNode = new N {
Payload = item.Action
};
var newState = GameLogic.Apply(context, clone.Clone(context.Source), item.Action);
double value = 0;
for (var i = 0; i < samplesPerAction; i++)
{
try {
var endState = Playout.Playout(context, clone.Clone(newState));
value += Evaluation.Evaluate(context, tempNode, endState);
SamplesUsedEvaluation++;
}
catch (Exception e) {
//Console.WriteLine($"ERROR: {e.GetType()} while cloning state.");
// TODO fix
// Cloning here seems to very seldom cause a NullReference in the SabberStone dll
// I believe failing and just using 0 as a value here is acceptable
}
}
item.Value = value;
}
// Return the half with the highest value.
var half = (int)Math.Max(1, Math.Ceiling(actions.Count / 2.0));
return(actions.OrderByDescending(i => i.Value).Take(half).ToList());
}