mixing_expansion(G, S, T=None, weight=None)¶
Returns the mixing expansion between two node sets.
The mixing expansion is the quotient of the cut size and twice the number of edges in the graph. 
- G (NetworkX graph)
- S (sequence) – A sequence of nodes in
- T (sequence) – A sequence of nodes in
- weight (object) – Edge attribute key to use as weight. If not specified, edges have weight one.
The mixing expansion between the two sets
 Vadhan, Salil P. “Pseudorandomness.” Foundations and Trends in Theoretical Computer Science 7.1–3 (2011): 1–336. <http://dx.doi.org/10.1561/0400000010>