使用networkx与我自己的对象

Question

我有我自己的对象，比如辣香肠。我有一份来自每个意大利辣香肠和一份胡椒粉的清单。然后我使用networkx构建一个图。我试图找到从一个意式香肠到另一个意式香肠的最短路径的重量。然而，我发现了一个错误，如下所示，它跟踪从networkx内在的东西如下：

Traceback (most recent call last): 


File "<stdin>", line 1, in <module> 
    File "pizza.py", line 437, in shortestPath 
    cost = nx.shortest_path_length(a, spepp, tpepp, True) 
    File "/Library/Python/2.6/site-packages/networkx-1.3-py2.6.egg/networkx/algorithms/shortest_paths/generic.py", line 181, in shortest_path_length 
    paths=nx.dijkstra_path_length(G,source,target) 
    File "/Library/Python/2.6/site-packages/networkx-1.3-py2.6.egg/networkx/algorithms/shortest_paths/weighted.py", line 119, in dijkstra_path_length 
    (length,path)=single_source_dijkstra(G,source, weight = weight) 
    File "/Library/Python/2.6/site-packages/networkx-1.3-py2.6.egg/networkx/algorithms/shortest_paths/weighted.py", line 424, in single_source_dijkstra 
    edata=iter(G[v].items()) 
    File "/Library/Python/2.6/site-packages/networkx-1.3-py2.6.egg/networkx/classes/graph.py", line 323, in __getitem__ 
    return self.adj[n] 
KeyError: <pizza.pepperoni object at 0x100ea2810> 

任何想法，什么是错误，或者我要为了添加到我的比萨类不算什么得到这个KeyError？

编辑：我有我的边格式正确。我不知道对象是否可以作为节点处理。

Answer 1

如果您将边缘和节点分别作为列表，则在网络x中构建图形很简单。鉴于在构建图形对象时发生的问题，也许是最好的诊断是一步要经过图形建设networkx步：

import networkx as NX 
import string 
import random 

G = NX.Graph() # initialize the graph 

# just generate some synthetic data for the nodes and edges: 
my_nodes = [ ch for ch in string.ascii_uppercase ] 
my_nodes2 = list(my_nodes) 
random.shuffle(my_nodes2) 
my_edges = [ t for t in zip(my_nodes, my_nodes2) if not t[0]==t[1] ] 

# now add the edges and nodes to the networkx graph object: 
G.add_nodes_from(my_nodes) 
G.add_edges_from(my_edges) 

# look at the graph's properties: 
In [87]: len(G.nodes()) 
Out[87]: 26 

In [88]: len(G.edges()) 
Out[88]: 25 

In [89]: G.edges()[:5] 
Out[89]: [('A', 'O'), ('A', 'W'), ('C', 'U'), ('C', 'F'), ('B', 'L')] 

# likewise, shortest path calculation is straightforward 
In [86]: NX.shortest_path(G, source='A', target='D', weighted=False) 
Out[86]: ['A', 'W', 'R', 'D'] 

以我的经验，Networkx有着极其宽容的接口，特别是，它将接受范围广泛的对象类型作为节点和边缘。节点可以是除None以外的任何可哈希对象。

我能想到的唯一的事情可能会导致您在您的问与答提出的错误是你装箱图形之后或许你直接操纵的图形对象（字典， * G *），您不应该做 - 有很多访问器方法。