def heuristic_low_tiles_gradient(board, old_board):
'''
Similar to :heuritic_gradient, we check for 2 and 4 tiles in the
given board and gradient-weight them depending on their position
and the importance of them being there.
The value is divided by the value of the old board and stays around 1.
'''
low_board = board.copy()
for row in low_board:
for cell in row:
if util._to_val(cell) > 4:
cell = 0
low_old_board = old_board.copy()
for row in low_old_board:
for cell in row:
if util._to_val(cell) > 4:
cell = 0
board_low_gradient = sum([b*g for b,g in zip(low_board.flatten(), low_goal_flat)])
old_board_low_gradient = sum([o*g for o,g in zip(low_old_board.flatten(), low_goal_flat)])
if (board_low_gradient == 0) or (old_board_low_gradient == 0):
return 1
return board_low_gradient / old_board_low_gradient
def _evaluate_tile_ratio(cell, neighbour_cell):
'''Compares two cells and returns their absolute difference in exponent'''
current_tile_exp = math.frexp(util._to_val(cell))[1]
neighbour_tile_exp = math.frexp(util._to_val(neighbour_cell))[1]
if neighbour_tile_exp == 0:
return current_tile_exp
ratio = current_tile_exp - neighbour_tile_exp
return math.fabs(ratio)
def heuristic_weighted_merge(move, board):
'''
Checks all possible tile-merges with the given move and
board and returns the score that is gained.
'''
score = 0.01
if move < 2:
'''UP/DOWN'''
for y in range(4):
if (board[0][y] == board[1][y]) and (util._to_val(board[0][y]) != 0):
'''merge in top spots, nonzero => XX??'''
score += board[0][y]
if (board[2][y] == board[3][y]) and (util._to_val(board[2][y]) != 0):
'''merge in whole row, nonzero => XXYY'''
score += board[2][y]
elif (board[1][y] == board[2][y]) and (util._to_val(board[1][y]) != 0):
'''merge in middle spots, nonzero => AXX?'''
score += board[1][y]
elif (board[2][y] == board[3][y]) and (util._to_val(board[2][y]) != 0):
'''merge in bottom spots, nonzero => ABXX'''
score += board[2][y]
else:
'''LEFT/RIGHT'''
for x in range(4):
if (board[x][0] == board[x][1]) and (util._to_val(board[x][0]) != 0):
'''merge in left spots, nonzero => XX??'''
score += board[x][0]
if (board[x][2] == board[x][3]) and (util._to_val(board[x][2]) != 0):
'''merge in whole column, nonzero => XXYY'''
score += board[x][2]
elif (board[x][1] == board[x][2]) and (util._to_val(board[x][1]) != 0):
'''merge in middle spots, nonzero => AXX?'''
score += board[x][1]
elif (board[x][2] == board[x][3]) and (util._to_val(board[x][2]) != 0):
'''merge in right spots, nonzero => ABXX'''
score += board[x][2]
'''x2 to match the resulting tile value instead of source tile values'''
return 2 * score
def heuristic_merge_count(move, board):
'''
TODO
'''
merges = 0
if move < 2:
'''UP/DOWN'''
for y in range(4):
if (board[0][y] == board[1][y]) and (util._to_val(board[0][y]) != 0):
'''merge in top spots, nonzero => XX??'''
merges += 1
if (board[2][y] == board[3][y]) and (util._to_val(board[2][y]) != 0):
'''merge in whole row, nonzero => XXYY'''
merges += 1
elif (board[1][y] == board[2][y]) and (util._to_val(board[1][y]) != 0):
'''merge in middle spots, nonzero => AXX?'''
merges += 1
elif (board[2][y] == board[3][y]) and (util._to_val(board[2][y]) != 0):
'''merge in bottom spots, nonzero => ABXX'''
merges += 1
else:
'''LEFT/RIGHT'''
for x in range(4):
if (board[x][0] == board[x][1]) and (util._to_val(board[x][0]) != 0):
'''merge in left spots, nonzero => XX??'''
merges += 1
if (board[x][2] == board[x][3]) and (util._to_val(board[x][2]) != 0):
'''merge in whole column, nonzero => XXYY'''
merges += 1
elif (board[x][1] == board[x][2]) and (util._to_val(board[x][1]) != 0):
'''merge in middle spots, nonzero => AXX?'''
merges += 1
elif (board[x][2] == board[x][3]) and (util._to_val(board[x][2]) != 0):
'''merge in right spots, nonzero => ABXX'''
merges += 1
'''x2 to match the resulting tile value instead of source tile values'''
return merges