This documents an unmaintained version of NetworkX. Please upgrade to a maintained version and see the current NetworkX documentation.


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.

  • 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.

nlist – List of nodes.

Return type:



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.