def __init__(self):
"""
Defines a goal state and initializes basic objects (heuristics, statistics).
"""
# State representation: tile value => (x,y)
self.goal_state = {
'tiles': {
1: (1,1), 2: (1,2), 3: (1,3),
8: (2,1), 0: (2,2), 4: (2,3),
7: (3,1), 6: (3,2), 5: (3,3)
},
'moved_tile': None,
'h_value': 0
}
# Basic objects
self.heuristics = PuzzleHeuristics(self.goal_state)
self.statistics = PuzzleStatistics(self)
class PuzzleWorld(object):
def __init__(self):
"""
Defines a goal state and initializes basic objects (heuristics, statistics).
"""
# State representation: tile value => (x,y)
self.goal_state = {
'tiles': {
1: (1,1), 2: (1,2), 3: (1,3),
8: (2,1), 0: (2,2), 4: (2,3),
7: (3,1), 6: (3,2), 5: (3,3)
},
'moved_tile': None,
'h_value': 0
}
# Basic objects
self.heuristics = PuzzleHeuristics(self.goal_state)
self.statistics = PuzzleStatistics(self)
# PUBLIC main methods
def solve_given_puzzle(self, start_state, h_type):
"""
Tries to solve a given puzzle with the selected heuristic.
Args:
start_state (Hash)
h_type (int):
1 ... MIN number of tiles on wrong positions.
2 ... MIN sum of manhattan distances from goal posisitions.
Returns:
boolean: Whether a solution from the start state has been found or not.
"""
# Reset solution path (start state -> goal state).
solution_path = []
# Add start state to the path.
solution_path.append(start_state)
current_state = solution_path[0]
current_state['h_value'] = self.heuristics.calculate_value(h_type,current_state)
# Search for a solution.
while current_state['tiles'] != self.goal_state['tiles']:
#print "======CUR STATE======"
#self._show_state(current_state)
# Find possible moves towards zero tile.
possible_moves = self._find_possible_moves(current_state)
# For every move create a new state.
new_states = self._create_states_from_moves(current_state, possible_moves)
# Check if the states are valid.
valid_states = self._get_valid_states(new_states, solution_path)
if not valid_states:
print('No solution found in %d moves (using h%d).') % (len(solution_path)-1, h_type)
return False
# Calculate heuristics value for every new state.
for state in valid_states:
state['h_value'] = self.heuristics.calculate_value(h_type,state)
# Choose state with the lowest heuristics value.
best_state = self._get_best_state(valid_states)
solution_path.append(best_state)
current_state = best_state
# Goal state was reached
print('The goal state was reached in %d moves (using h%d).') % (len(solution_path)-1,h_type)
#print(solution_path)
return solution_path
def solve_random_puzzle(self, h_type):
"""
Solve a randomly generated puzzle (using given h type).
"""
result = self.solve_given_puzzle(self.generate_start_state(), h_type)
return result
# PUBLIC statistical methods
def bulk_solve(self, number_of_puzzles, h_type):
"""
Perform a simulation of solving many puzzles at once (using given h type).
"""
self.statistics.bulk_solve(number_of_puzzles, h_type)
def bulk_solve_compare(self, number_of_puzzles):
"""
Compare both heuristics by performing a simulation.
"""
self.statistics.solve_and_compare_bulk(number_of_puzzles)
# PUBLIC working methods
def generate_start_state(self):
"""
Generates a random start state.
"""
state_a = {
'tiles': {
5: (1,1), 4: (1,2), 0: (1,3),
6: (2,1), 1: (2,2), 8: (2,3),
7: (3,1), 3: (3,2), 2: (3,3)
},
'moved_tile': None,
'h_value': None
}
random_tiles = {i: None for i in range(0,9)}
positions_used = []
i = 0
while i < 9:
r_pos = (random.randint(1,3), random.randint(1,3))
if r_pos not in positions_used:
positions_used.append(r_pos)
random_tiles[i] = r_pos
i += 1
r_state = {
'tiles': random_tiles, 'moved_tile': None, 'h_value': None
}
print random_tiles
return r_state
# PRIVATE working methods
def _find_possible_moves(self, current_state):
"""
Returns tiles with which the zero tile can change its position.
Args:
current_state (Hash)
Returns:
list
"""
# Get zero tile coordinates
tile_zero = current_state['tiles'][0]
# Count new coordinates for 4 movements.
x_up = tile_zero[0] - 1
x_down = tile_zero[0] + 1
y_left = tile_zero[1] - 1
y_right = tile_zero[1] + 1
#print tile_zero, x_down, x_up, y_left, y_right
# Check coordinates
movable_tiles= []
if x_up > 0 and x_up <= 3:
movable_tiles.append((x_up, tile_zero[1]))
if x_down > 0 and x_down <= 3:
movable_tiles.append((x_down, tile_zero[1]))
if y_left > 0 and y_left <= 3:
movable_tiles.append((tile_zero[0],y_left))
if y_right > 0 and y_right <= 3:
movable_tiles.append((tile_zero[0],y_right))
# Result
return movable_tiles
def _create_states_from_moves(self, current_state, possible_moves):
"""
Create new states from given moves.
Args:
current_state (Hash)
possible_moves: List of tiles with which the zero tile can change its position.
Returns:
list: new states
"""
new_states = []
zero_tile = current_state['tiles'][0]
for moved_tile in possible_moves:
new_zero = moved_tile
new_move_tile = zero_tile
new_state = {}
new_state['tiles'] = current_state['tiles'].copy()
new_state['tiles'][0] = new_zero
new_state['tiles'][self._get_tile_name_by_coordinates(current_state, moved_tile)] = new_move_tile
new_state['moved_tile'] = moved_tile
new_states.append(new_state)
# result
return new_states
def _get_valid_states(self, new_states, solution_path):
"""
Eliminate all already visited states (in solution path).
"""
valid_states = []
for new_state in new_states:
ok = True
for sel_state in solution_path:
if sel_state['tiles'] == new_state['tiles']:
ok = False
break
if ok:
valid_states.append(new_state)
# result
return valid_states
def _get_best_state(self, valid_states):
"""
Select a state with the lowest h value.
[Not implemented: If there are more states with same value, choose the one which will place a non-zero title on the right place.]
"""
return min(valid_states, key=lambda x: x['h_value'])
# HELPER functions
def _get_tile_name_by_coordinates(self, state, coordinates):
"""
Given x and y, return tile name from the given state.
"""
for t_name, xy in state['tiles'].iteritems():
if xy == coordinates:
return t_name
def _show_state(self, state):
"""
A nice matrix representation of the state could be shown, but it's difficlut :).
"""
print(state)
