networkx.algorithms.core.k_shell¶

k_shell(G, k=None, core_number=None)[source]¶

Returns the k-shell of G.

The k-shell is the subgraph induced by nodes with core number k. That is, nodes in the k-core that are not in the (k+1)-core.

Parameters

G (NetworkX graph) – A graph or directed graph.
k (int, optional) – The order of the shell. If not specified return the outer shell.
core_number (dictionary, optional) – Precomputed core numbers for the graph G.

Returns

G – The k-shell subgraph

Return type

NetworkX graph

Raises

NetworkXError – The k-shell is not implemented for graphs with self loops or parallel edges.

Notes

This is similar to k_corona but in that case only neighbors in the k-core are considered.

Not implemented for graphs with parallel edges or self loops.

For directed graphs the node degree is defined to be the in-degree + out-degree.

Graph, node, and edge attributes are copied to the subgraph.