node_boundary(G, nbunch1, nbunch2=None)[source]

Return the node boundary.

The node boundary is all nodes in the edge boundary of a given set of nodes that are in the set.

Parameters :

G : graph

A networkx graph

nbunch1 : list, container

Interior node set

nbunch2 : list, container

Exterior node set. If None then it is set to all of the nodes in G not in nbunch1.

Returns :

nlist : list

List of nodes.


Nodes in nbunch1 and nbunch2 that are not in G are ignored.

nbunch1 and nbunch2 are usually meant to be disjoint, but in the interest of speed and generality, that is not required here.