学习Python中A*算法实现的详细步骤

def aStarAlgo(start_node,stop_node):
open_set=set(start_node)
closed_set=set()
g={}
parents={}
g[start_node]=0
parents[start_node]=start_node

While len(open_set)>0:
n=None
for v in open_set:
if n==None or g[v]+heuristic(v)<g[n]+heuristic(n):
n=v
if n==stop_node or Graph_nodes[n]==None:
pass
else:
for(m,weight)in get_neighbors(n):
if m not in open_set and m not in closed_set:
open_set.add(m)
parents[m]=n
g[m]=g[n]+weight

else:
if g[m]>g[n]+weight:
g[m]=g[n]+weight
parents[m]=n
if m in closed_set:
closed_set.remove(m)
open_set.add(m)

if n==None:
print('Path does not exist!')
return None
if n==stop_node:
path=[]
while parents[n]!=n:
path.append(n)
n=parents[n]
path.append(start_node)
path.reverse()
print('Path found:{}'.format(path))
return path
open_set.remove(n)
closed_set.add(n)
print('Path does not exist!')
return None

def get_neighbors(v):
if v in Graph_nodes:
return Graph_nodes[v]
else:
return None

def heuristic(n):
H_dist={
'A':11,
'B':6,
'C':99,
'D':1,
'E':7,
'G':0,
}
return H_dist[n]

Graph_nodes={
'A':[('B',2),('E',3)],
'B':[('C',1),('G',9)],
'C':Node,
'E':[('D',6)],
'D':[('G',1)],
}
aStarAlgo('A','G')