python实现Floyd算法

下面是用Python实现Floyd算法的代码，供大家参考，具体内容如下

# -*- coding: utf-8 -*-
"""
Created on Thu Jul 13 14:56:37 2017

@author: linzr
"""

## 表示无穷大
INF_val = 9999

class Floyd_Path():
def __init__(self, node, node_map, path_map):
 self.node = node
 self.node_map = node_map
 self.node_length = len(node_map)
 self.path_map = path_map
 self._init_Floyd()

def __call__(self, from_node, to_node):
 self.from_node = from_node
 self.to_node = to_node
 return self._format_path()

def _init_Floyd(self):
 for k in range(self.node_length):
  for i in range(self.node_length):
   for j in range(self.node_length):
    tmp = self.node_map[i][k] + self.node_map[k][j]
    if self.node_map[i][j] > tmp:
     self.node_map[i][j] = tmp
     self.path_map[i][j] = self.path_map[i][k]

print '_init_Floyd is end'

def _format_path(self):
 node_list = []
 temp_node = self.from_node
 obj_node = self.to_node
 print("the shortest path is: ％d")％(self.node_map[temp_node][obj_node])
 node_list.append(self.node[temp_node])
 while True:
  node_list.append(self.node[self.path_map[temp_node][obj_node]])
  temp_node = self.path_map[temp_node][obj_node]
  if temp_node == obj_node:
   break;

return node_list

def set_node_map(node_map, node, node_list, path_map):
for i in range(len(node)):
 ## 对角线为0
 node_map[i][i] = 0
for x, y, val in node_list:
 node_map[node.index(x)][node.index(y)] = node_map[node.index(y)][node.index(x)] = val
 path_map[node.index(x)][node.index(y)] = node.index(y)
 path_map[node.index(y)][node.index(x)] = node.index(x)

if __name__ == "__main__":
node = ['A', 'B', 'C', 'D', 'E', 'F', 'G']
node_list = [('A', 'F', 9), ('A', 'B', 10), ('A', 'G', 15), ('B', 'F', 2),
    ('G', 'F', 3), ('G', 'E', 12), ('G', 'C', 10), ('C', 'E', 1),
    ('E', 'D', 7)]

## node_map[i][j] 存储i到j的最短距离
node_map = [[INF_val for val in xrange(len(node))] for val in xrange(len(node))]
## path_map[i][j]=j 表示i到j的最短路径是经过顶点j
path_map = [[0 for val in xrange(len(node))] for val in xrange(len(node))]

## set node_map
set_node_map(node_map, node, node_list, path_map)

## select one node to obj node, e.g. A --> D(node[0] --> node[3])
from_node = node.index('A')
to_node = node.index('E')
Floydpath = Floyd_Path(node, node_map, path_map)
path = Floydpath(from_node, to_node)
print path

运行结果为：
the shortest path is: 23
['A', 'F', 'G', 'C', 'E']

来源：http://blog.csdn.net/u011285477/article/details/75096303