/// <summary>
/// Prints the best path
/// </summary>
private static void PrintPath(MazeEnvironment environment, MazeAgent agent)
{
var learner = agent.Learner as QLearning <MazeState>;
var path = new HashSet <MazeState>();
MazeState state = environment.GetDefaultState(agent);
path.Add(state);
while (true)
{
MazeAction action = (MazeAction)learner.SelectAction(state);
switch (action)
{
case MazeAction.Up:
state = state.Add(y: -1);
break;
case MazeAction.Down:
state = state.Add(y: 1);
break;
case MazeAction.Right:
state = state.Add(x: 1);
break;
case MazeAction.Left:
state = state.Add(x: -1);
break;;
}
path.Add(state);
if (environment.Tiles[state.PositionX, state.PositionY] == MazeTile.Goal)
{
break;
}
}
for (int y = 0; y < environment.Length; y++)
{
for (int x = 0; x < environment.Width; x++)
{
switch (environment.Tiles[x, y])
{
case MazeTile.Floor:
if (path.Contains(new MazeState(x, y)))
{
Console.Write("x");
}
else
{
Console.Write(" ");
}
break;
case MazeTile.Wall:
Console.Write("W");
break;
case MazeTile.Agent:
Console.Write("A");
break;
case MazeTile.Goal:
Console.Write("G");
break;
}
}
Console.WriteLine();
}
}
/// <summary>
/// Executes the given action for the given agent
/// </summary>
/// <param name="agent">The agent</param>
/// <param name="actionNumber">The index of the action</param>
/// <param name="episode">The current episode number</param>
public override void Execute(MazeAgent agent, int actionNumber, int episode)
{
MazeAction action = (MazeAction)actionNumber;
int newPosX = agent.State.PositionX;
int newPosY = agent.State.PositionY;
switch (action)
{
case MazeAction.Up:
newPosY--;
break;
case MazeAction.Down:
newPosY++;
break;
case MazeAction.Right:
newPosX++;
break;
case MazeAction.Left:
newPosX--;
break;
}
//Check if the new position is valid
bool valid = true;
if ((newPosX >= 0 && newPosX < this.Width) && (newPosY >= 0 && newPosY < this.Length))
{
var newTileType = this.tiles[newPosX, newPosY];
if (newTileType != MazeTile.Wall)
{
var newState = new MazeState(newPosX, newPosY);
bool isTerminal = newTileType == MazeTile.Goal;
//Update the world & agent
this.tiles[agent.State.PositionX, agent.State.PositionY] = MazeTile.Floor;
this.tiles[newPosX, newPosY] = MazeTile.Agent;
agent.State = newState;
//Calculate the reward
agent.Reward(this.CalculateReward(isTerminal), isTerminal, episode);
}
else
{
valid = false;
}
}
else
{
valid = false;
}
if (!valid)
{
agent.State = agent.State;
agent.Reward(this.CalculateReward(false), false, episode);
}
}
