54 lines
1.6 KiB
C#
54 lines
1.6 KiB
C#
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using OECS;
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namespace OECS.PlayTest;
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/// <summary>
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/// Abstract agent that picks the action with the highest score.
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/// When <see cref="ScoreAction"/> returns 0 for all actions (the default),
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/// the agent behaves as a uniform random agent over legal actions.
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/// Ties are broken randomly.
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/// </summary>
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public abstract class GreedyAgent<TDecision> : IAgent<TDecision>
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{
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private static readonly Random _rng = new();
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/// <summary>
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/// Returns the list of currently legal actions.
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/// </summary>
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protected abstract List<TDecision> GetLegalActions(World world);
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/// <summary>
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/// Scores an action. Defaults to 0 (uniform random).
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/// </summary>
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protected virtual float ScoreAction(World world, TDecision action) => 0f;
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public TDecision Decide(World world)
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{
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var actions = GetLegalActions(world);
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if (actions.Count == 0)
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throw new InvalidOperationException(
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$"{GetType().Name}: no legal actions available");
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if (actions.Count == 1)
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return actions[0];
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float bestScore = float.MinValue;
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var bestActions = new List<TDecision>();
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foreach (var action in actions)
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{
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float score = ScoreAction(world, action);
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if (score > bestScore)
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{
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bestScore = score;
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bestActions.Clear();
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bestActions.Add(action);
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}
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else if (score == bestScore)
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{
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bestActions.Add(action);
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}
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}
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return bestActions[_rng.Next(bestActions.Count)];
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}
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}
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