networkx.algorithms.graphical.is_digraphical

is_digraphical(in_sequence, out_sequence)

Returns True if some directed graph can realize the in- and out-degree sequences.

Parameters

• in_sequence (list or iterable container) – A sequence of integer node in-degrees

• out_sequence (list or iterable container) – A sequence of integer node out-degrees

Returns

valid – True if in and out-sequences are digraphic False if not.

Return type

bool

Notes

This algorithm is from Kleitman and Wang 1. The worst case runtime is $O(s \times \log n)$ where $s$ and $n$ are the sum and length of the sequences respectively.

References

1

D.J. Kleitman and D.L. Wang Algorithms for Constructing Graphs and Digraphs with Given Valences and Factors, Discrete Mathematics, 6(1), pp. 79-88 (1973)