[英]Breadth First Search with list of coordinates python
我正在為“蜘蛛游戲”(與蛇游戲幾乎相同的概念,但移動邏輯有些不同)構建一個簡單的AI。 我正在嘗試實現BFS算法,以便蜘蛛能夠找到將其引導至螞蟻的路徑。 該算法似乎可以進行多次迭代,但是當我在調試器之外運行它時,它會在node_list
內獲得None
值,這會使其他方法失敗(因為您無法繼續下一步)。
這是BFS算法:
def BFS(spider_state, ant_state):
goal = False
count = 0
initial_node = Node(spider_state, None, 0)
node_list = [initial_node]
initial_ant_state = ant_state
while goal == False or len(node_list) == 0:
e = node_list.pop(0)
future_ant_state = initial_ant_state
for i in range(0, e.depth):
future_ant_state = get_next_ant_move(border_choice, initial_ant_state)
for move in POSSIBLE_MOVES:
count += 1
next_node = Node(None, None, None)
next_node.state = get_next_spider_move(deepcopy(e.state), move)
next_node.parent = e
next_node.depth = e.depth + 1
if next_node.state == future_ant_state:
goal = True
break
else:
node_list.append(next_node)
return node_list
節點:
class Node():
def __init__(self, state, parent, depth):
self.state = state
self.parent = parent
self.depth = depth
蜘蛛和螞蟻表示為x
和y
位置的簡單列表:
spider = [15, 35]
ant = [20, 10]
get next move
方法如下所示:
def get_next_spider_move(spidy, move):
if spidy:
# check the bounds and assign the new value to spidy
spidy = spider_bounds(spidy)
# farthest right
if move == 0:
spidy[1] += 2
spidy[0] -= 1
# furhter up and right
if move == 1:
spidy[1] += 1
spidy[0] -= 2
# backwords
if move == 2:
spidy[0] += 1
# farthest left
if move == 3:
spidy[1] -= 2
spidy[0] -= 1
# furhter up and to the left
if move == 4:
spidy[1] += 1
spidy[0] -= 2
# one left
if move == 5:
spidy[1] -= 1
# one right
if move == 6:
spidy[1] -= 1
# side right
if move == 7:
spidy[1] += 1
spidy[0] += 1
# side left
if move == 8:
spidy[1] -= 1
spidy[0] -= 1
else:
# if no valid direction was given
return spidy
else:
raise ValueError('spidy must contain an x and y position. %s', spidy, ' was found')
運行時產生的錯誤:
File "spider_game_bfs.py", line 141, in <module>
path = BFS(spider, ant)
File "spider_game_bfs.py", line 130, in BFS
next_node.state = get_next_spider_move(deepcopy(e.state), move)
File "spider_game_bfs.py", line 100, in get_next_spider_move
raise ValueError('spidy must contain an x and y position. %s', spidy, ' was found')
ValueError: ('spidy must contain an x and y position. %s', None, ' was found')
您的移動功能底部有一個邏輯錯誤。 最后一個完整的語句是
if move == 8:
spidy[1] -= 1
spidy[0] -= 1
else:
# if no valid direction was given
return spidy
您的評論是不正確的:在else
比8, 其他任何行動。如果此舉是 8返回條款被執行,則None
,因為你已經跳過返回的聲明spidy
。
如第一條評論所述,如果將if ... elif ... else
作為您的邏輯結構,您會做得更好。 甚至比這更好的是,遵循許多移動項目的在線示例:列出移動的清單或命令,如下所示:
move_dir = [
(-1, +2), # move 0
(-2, +1), # move 1
(+1, 0), # move 2
... # fill in the rest
]
if move in range(len(move_dir)):
spidy[0] += move_dir[move[0]]
spidy[1] += move_dir[move[1]]
return spidy
else:
raise ValueError ...
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