测试图形是Edgelist文件中的有向图还是无向图

Question

I have a text document that is an edge list file. I know how to read the file (using Canopy Enthought), but I don't know how to get the information about the graph that I want.

Main question : Is there a way to detect whether this graph (created from the edge list file) is directed or undirected using networkx commands? Or just if it is weighted or unweighed?

Answer 1

I believe that you have to specify the type of the graph before using the edge list file. Because the edge list file is simply composed of tuples containing nodes to be connected without saying how they are connected. Thus, for instance if you create a graph G = nx.Graph() , then if the node pairs in the file are repeated, there will still be one edge between them and the order of the nodes does not matter; ((node1,node2) is equivalent to (node2,node1)). While if you created the graph as G = nx.DiGraph() the order of nodes makes a difference. Also, specifying G = nx.MultiGraph() more than one edge will exist in case of repetition. G = nx.MultiDiGraph() will have a different result when reading the edge list file. So, check the the graph types documentation to know which type you need to have.

To check if the graph is directed you can use nx.is_directed(G) , you can find the documentation here .

To check if the graph is weighted There is no specific type to say if the graph has weighted edges or not. But a work around can be to check if edges contain an attribute called weight , as mentioned here . It can be done by

'weight' in G[1][2] # Returns true if an attribute called weight exists in the edge connecting nodes 1 and 2.