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Node.py
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Node.py
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import copy
from utils import find, getLowestCost
class Node:
goal1 = [[1,2,3,4],[5,6,7,0]]
goal2 = [[1,3,5,7],[2,4,6,0]]
def __init__(self, state, parent, tileMoved, cost, max_row, max_col):
self.state = state
self.parent = parent
self.successors = []
self.tileMoved = tileMoved
self.cost = cost
self.fn = 0
self.gn = 0
self.hn = 0
self.max_row = max_row
self.max_col = max_col
self.emptyPos = find(self.state, 0)
def isCorner(self, coord):
(row, col) = coord
if row == 0 and col == 0:
return 'tl'
elif row == self.max_row and col == self.max_col:
return 'br'
elif row == self.max_row and col == 0:
return 'bl'
elif row == 0 and col == self.max_col:
return 'tr'
return None
def generateSuccessors(self):
empty = self.emptyPos
self.move_up(empty)
self.move_down(empty)
self.move_left(empty)
self.move_right(empty)
if(self.isCorner(empty) != None):
self.wrap_left(empty)
self.wrap_right(empty)
self.diag_downleft(empty)
self.diag_downright(empty)
self.diag_upleft(empty)
self.diag_upright(empty)
self.diag_opposite(empty, self.isCorner(empty))
if(self.max_row > 2):
self.wrap_up(empty)
self.wrap_down(empty)
# Regular moves: Cost = 1
def move_up(self, emptyTile):
row, col = emptyTile
if(row-1 >= 0):
targetTile = (row-1, col)
self.swap_and_add_child(emptyTile, targetTile, 1)
def move_down(self, emptyTile):
(row, col) = emptyTile
if(row+1 <= self.max_row):
targetTile = (row+1, col)
self.swap_and_add_child(emptyTile, targetTile, 1)
def move_left(self, emptyTile):
(row, col) = emptyTile
if(col-1 >= 0):
targetTile = (row, col-1)
self.swap_and_add_child(emptyTile, targetTile, 1)
def move_right(self, emptyTile):
(row, col) = emptyTile
if(col+1 <= self.max_col):
targetTile = (row, col+1)
self.swap_and_add_child(emptyTile, targetTile, 1)
# Wrap moves: Cost = 2
def wrap_left(self, emptyTile):
(row, _) = emptyTile
targetTile = (row, 0)
self.swap_and_add_child(emptyTile, targetTile, 2)
def wrap_right(self, emptyTile):
(row, _) = emptyTile
targetTile = (row, self.max_col)
self.swap_and_add_child(emptyTile, targetTile, 2)
def wrap_up(self, emptyTile):
(_, col) = emptyTile
targetTile = (0, col)
self.swap_and_add_child(emptyTile, targetTile, 2)
def wrap_down(self, emptyTile):
(_, col) = emptyTile
targetTile = (self.max_row, col)
self.swap_and_add_child(emptyTile, targetTile, 2)
# Diagonal moves: Cost = 3
def diag_downleft(self, emptyTile):
(row, col) = emptyTile
if(row + 1 <= self.max_row and col - 1 >= 0):
targetTile = (row+1, col-1)
self.swap_and_add_child(emptyTile, targetTile, 3)
def diag_downright(self, emptyTile):
(row, col) = emptyTile
if(row + 1 <= self.max_row and col + 1 <= self.max_col):
targetTile = (row+1, col+1)
self.swap_and_add_child(emptyTile, targetTile, 3)
def diag_upleft(self, emptyTile):
(row, col) = emptyTile
if(row - 1 >=0 and col - 1 >= 0):
targetTile = (row-1, col-1)
self.swap_and_add_child(emptyTile, targetTile, 3)
def diag_upright(self, emptyTile):
(row, col) = emptyTile
if(row - 1 >= 0 and col + 1 <= self.max_col):
targetTile = (row-1, col+1)
self.swap_and_add_child(emptyTile, targetTile, 3)
def diag_opposite(self, emptyTile, cornerPos):
if(cornerPos == 'tl'):
targetTile = (self.max_row, self.max_col)
elif(cornerPos == 'tr'):
targetTile = (self.max_row, 0)
elif(cornerPos == 'bl'):
targetTile = (0, self.max_col)
else:
targetTile = (0, 0)
self.swap_and_add_child(emptyTile, targetTile, 3)
def swap_and_add_child(self, emptyTile, targetTile, move_cost):
new_state = copy.deepcopy(self.state)
t_row, t_col = targetTile
e_row, e_col = emptyTile
value_target = new_state[t_row][t_col]
new_state[e_row][e_col] = value_target
new_state[t_row][t_col] = 0
child = Node(new_state, self, value_target, move_cost, self.max_row, self.max_col)
self.successors.append(child)
def isGoal(self, state):
if(state == Node.goal1 or state == Node.goal2):
return True
return False
def traceSolution(self, moves, costs, path):
moves.append(self.tileMoved)
costs.append(self.cost)
path.append(self.state)
if self.parent == None:
return (moves, costs, path)
else:
return self.parent.traceSolution(moves, costs, path)
# Applies heuristic to node
def h(self, heur):
if heur == 'h0':
return self.h0()
elif heur == 'h1':
return self.h1()
elif heur == 'h2':
return self.h2()
else:
print('invalid heuristic')
# Heuristic 0 logic (provided in assignment instructions)
def h0(self):
if (self.state[self.max_row][self.max_col] == 0):
return 0
return 1
# Heuristic 1 logic (custom heuristic)
def h1(self):
total_cost1 = 0
total_cost2 = 0
for row in range(self.max_row + 1):
for col in range(self.max_col + 1):
if self.state[row][col] != Node.goal1[row][col]:
goal_r, goal_c = find(Node.goal1, self.state[row][col])
total_cost1 += getLowestCost(row, col, goal_r, goal_c)
if self.state[row][col] != Node.goal2[row][col]:
goal_r, goal_c = find(Node.goal2, self.state[row][col])
total_cost2 += getLowestCost(row, col, goal_r, goal_c)
return min(total_cost1,total_cost2)
# Heuristic 2 logic (hamming distance + custom heuristic h1)
def h2(self):
goal1_hd = 0
goal2_hd = 0
for row in range(self.max_row + 1):
for col in range(self.max_col + 1):
if(self.state[row][col] != 0):
if self.state[row][col] != Node.goal1[row][col]:
goal1_hd += 1
if self.state[row][col] != Node.goal2[row][col]:
goal2_hd += 1
if(goal1_hd < goal2_hd):
total_cost = 0
for row in range(self.max_row + 1):
for col in range(self.max_col + 1):
if self.state[row][col] != Node.goal1[row][col]:
goal_r, goal_c = find(Node.goal1, self.state[row][col])
total_cost += getLowestCost(row, col, goal_r, goal_c)
return total_cost
else:
total_cost = 0
for row in range(self.max_row + 1):
for col in range(self.max_col + 1):
if self.state[row][col] != Node.goal2[row][col]:
goal_r, goal_c = find(Node.goal2, self.state[row][col])
total_cost += getLowestCost(row, col, goal_r, goal_c)
return total_cost