contracted_edge(G, edge, self_loops=True, copy=True)
Edge contraction identifies the two endpoints of the edge as a single node incident to any edge that was incident to the original two nodes. A graph that results from edge contraction is called a minor of the original graph.
The graph whose edge will be contracted.
Must be a pair of nodes in G.
If this is True, any edges (including :None:None:`edge`) joining the endpoints of :None:None:`edge` in G become self-loops on the new node in the returned graph.
If this is True, a the contraction will be performed on a copy of G, otherwise the contraction will happen in place.
If :None:None:`edge` is not an edge in G.
A new graph object of the same type as G (leaving G unmodified) with endpoints of :None:None:`edge` identified in a single node. The right node of :None:None:`edge` will be merged into the left one, so only the left one will appear in the returned graph.
Returns the graph that results from contracting the specified edge.
Attempting to contract two nonadjacent nodes yields an error:
This example is valid syntax, but raise an exception at execution>>> G = nx.cycle_graph(4)
... nx.contracted_edge(G, (1, 3)) Traceback (most recent call last): ... ValueError: Edge (1, 3) does not exist in graph G; cannot contract it
Contracting two adjacent nodes in the cycle graph on n nodes yields the cycle graph on n - 1 nodes:
>>> C5 = nx.cycle_graph(5)See :
... C4 = nx.cycle_graph(4)
... M = nx.contracted_edge(C5, (0, 1), self_loops=False)
... nx.is_isomorphic(M, C4) True
The following pages refer to to this document either explicitly or contain code examples using this.
networkx.algorithms.minors.contraction.contracted_nodes
networkx.algorithms.minors.contraction.contracted_edge
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