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']