contracted_nodes¶

contracted_nodes(G, u, v, self_loops=True)[source]¶

Returns the graph that results from contracting u and v.

Node contraction identifies the two nodes as a single node incident to any edge that was incident to the original two nodes.

Parameters:	G (NetworkX graph) – The graph whose nodes will be contracted. v (u,) – Must be nodes in `G`. self_loops (Boolean) – If this is `True`, any edges joining `u` and `v` in `G` become self-loops on the new node in the returned graph.
Returns:	A new graph object of the same type as `G` (leaving `G` unmodified) with `u` and `v` identified in a single node. The right node `v` will be merged into the node `u`, so only `u` will appear in the returned graph.
Return type:	Networkx graph

Examples

Contracting two nonadjacent nodes of the cycle graph on four nodes \(C_4\) yields the path graph (ignoring parallel edges):

>>> import networkx as nx
>>> G = nx.cycle_graph(4)
>>> M = nx.contracted_nodes(G, 1, 3)
>>> P3 = nx.path_graph(3)
>>> nx.is_isomorphic(M, P3)
True