def __init__(self, name):
"""
Create the player.
"""
self.name = name
self.learning = True
self.input_scale = 16.0
self.selectivity = 0.0
self.neural_net = BoardgameNeuralNet(num_inputs=9,
num_hidden_layers=1,
num_hidden_units=[250],
step_size=3E-1,
regulariser=3E-2)
class LearningNoughtsAndCrossesPlayer(Player):
"""
A learning computer player for noughts and crosses. Uses a neural net to
estimate the probability of winning from any state (when the opponent is
about to play).
"""
strategies = ["win", "block"]
symmetry_maps = np.array([[2,5,8,1,4,7,0,3,6],
[8,7,6,5,4,3,2,1,0],
[6,3,0,7,4,1,8,5,2],
[6,7,8,3,4,5,0,1,2],
[2,1,0,5,4,3,8,7,6],
[0,3,6,1,4,7,2,5,8],
[8,5,2,7,4,1,6,3,0]])
def __init__(self, name):
"""
Create the player.
"""
self.name = name
self.learning = True
self.input_scale = 16.0
self.selectivity = 0.0
self.neural_net = BoardgameNeuralNet(num_inputs=9,
num_hidden_layers=1,
num_hidden_units=[250],
step_size=3E-1,
regulariser=3E-2)
#momentum=0.0,
#dropout_rate=0)
def move(self, board):
"""
Obtain a move.
"""
legal_moves = board.permitted_moves
log_prob = np.zeros((len(legal_moves),3))
options = dict()
for st in self.strategies:
options[st] = []
# Loop through the opponents possible moves
for mv in legal_moves:
bd = board.copy()
bd.turn = -bd.turn
bd.move(mv)
# See if they won (or if it was a draw)
if bd.over:
options['block'].append(mv)
# Loop through possible moves
for mm in range(len(legal_moves)):
mv = legal_moves[mm]
bd = board.copy()
bd.move(mv)
# See if we won (or it was a draw)
if bd.over:
options['win'].append(mv)
# Estimate probability of winning
state = bd.state.flatten()[np.newaxis,:]
log_prob[mm,:] = self.neural_net.predict(state/self.input_scale)
#print("Log-probability of 0/+1/-1 victory if I make move {} "
# "is {}/{}/{}.".format(state, *prob[mm,:]))
# Decide which option to take
move = None
for st in self.strategies:
if options[st]:
move = np.random.choice(options[st])
break
if move is None:
# Calculated expected return (+1 for win, -1 for loss, 0 for draw)
expct_return = np.exp(log_prob[:,board.turn]) \
- np.exp(log_prob[:,-board.turn])
if (self.learning and (np.random.rand() < self.selectivity)):
move = np.random.choice(legal_moves)
else:
move = legal_moves[np.argmax(expct_return)]
#select_prob = np.exp(expct_return/self.selectivity)
#select_prob /= np.sum(select_prob)
#move = np.random.choice(legal_moves, p=select_prob)
# Store the board for learning later
board.move(move)
self._game_history.append(board.state.flatten())
return move
def learn(self, winner):
"""
Update net.
"""
if self.learning:
# Parse the game history to make training data
states = np.array(self._game_history)
states = self.symmetric_equivalents(states)
outputs = winner*np.ones(states.shape[0], dtype=int)
# Update the net
self.neural_net.update(states/self.input_scale, outputs)
def notify(self, event, info):
"""
Act on an event notification from the game.
"""
if (event == "begin"):
self._game_history = []
elif (event == "finish"):
self.learn(info)
else:
pass
def symmetric_equivalents(self, states):
"""
Add symmetrically identical states to an array of game states.
"""
for state in states.copy():
symmetries = self.symmetries(state)
for sym in symmetries:
if not np.any((states==sym).all(axis=1)):
states = np.vstack((states, sym))
return states
def symmetries(self, state):
"""
Make a list of all the states obtainable by reflecting or rotating
a base state.
"""
syms = []
for ii in range(7):
syms.append(state[self.symmetry_maps[ii,:]])
return syms
