contracted_nodes(G, u, v, self_loops=True)¶
Returns the graph that results from contracting
Node contraction identifies the two nodes as a single node incident to any edge that was incident to the original two nodes.
- G (NetworkX graph) – The graph whose nodes will be contracted.
- u, v (nodes) – Must be nodes in
- self_loops (Boolean) – If this is True, any edges joining
Gbecome self-loops on the new node in the returned graph.
A new graph object of the same type as
videntified in a single node. The right node
vwill be merged into the node
u, so only
uwill appear in the returned graph.
For multigraphs, the edge keys for the realigned edges may not be the same as the edge keys for the old edges. This is natural because edge keys are unique only within each pair of nodes.
Contracting two nonadjacent nodes of the cycle graph on four nodes
C_4yields the path graph (ignoring parallel edges):
>>> G = nx.cycle_graph(4) >>> M = nx.contracted_nodes(G, 1, 3) >>> P3 = nx.path_graph(3) >>> nx.is_isomorphic(M, P3) True >>> G = nx.MultiGraph(P3) >>> M = nx.contracted_nodes(G, 0, 2) >>> M.edges MultiEdgeView([(0, 1, 0), (0, 1, 1)]) >>> G = nx.Graph([(1,2), (2,2)]) >>> H = nx.contracted_nodes(G, 1, 2, self_loops=False) >>> list(H.nodes())  >>> list(H.edges()) [(1, 1)]
This function is also available as