line_graph¶

line_graph
(G, create_using=None)[source]¶ Return the line graph of the graph or digraph G.
The line graph of a graph G has a node for each edge in G and an edge between those nodes if the two edges in G share a common node. For directed graphs, nodes are connected only if they form a directed path of length 2.
The nodes of the line graph are 2tuples of nodes in the original graph (or 3tuples for multigraphs, with the key of the edge as the 3rd element).
For more discussion, see the docstring in
networkx.generators.line
.Parameters: G : graph
A NetworkX Graph, DiGraph, MultiGraph, or MultiDigraph.
Returns: L : graph
The line graph of G.
Notes
Graph, node, and edge data are not propagated to the new graph. For undirected graphs, the nodes in G must be sortable—otherwise, the constructed line graph may not be correct.
Examples
>>> G = nx.star_graph(3) >>> L = nx.line_graph(G) >>> print(sorted(L.edges())) # makes a clique, K3 [((0, 1), (0, 2)), ((0, 1), (0, 3)), ((0, 3), (0, 2))]