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Note

This documents the development version of NetworkX. Documentation for the current release can be found here.

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networkx.algorithms.graphical.is_digraphical

is_digraphical(in_sequence, out_sequence)[source]

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)