U 9v f3ã@s4dZddlZddlmZdgZedƒddd„ƒZdS)a–Generators for cographs A cograph is a graph containing no path on four vertices. Cographs or $P_4$-free graphs can be obtained from a single vertex by disjoint union and complementation operations. References ---------- .. [0] D.G. Corneil, H. Lerchs, L.Stewart Burlingham, "Complement reducible graphs", Discrete Applied Mathematics, Volume 3, Issue 3, 1981, Pages 163-174, ISSN 0166-218X. éN)Úpy_random_stateÚrandom_cographécs^t d¡‰t|ƒD]F}t ˆ ¡‡fdd„¡}| dd¡dkrLt ˆ|¡‰qt ˆ|¡‰qˆS)aôReturns a random cograph with $2 ^ n$ nodes. A cograph is a graph containing no path on four vertices. Cographs or $P_4$-free graphs can be obtained from a single vertex by disjoint union and complementation operations. This generator starts off from a single vertex and performs disjoint union and full join operations on itself. The decision on which operation will take place is random. Parameters ---------- n : int The order of the cograph. seed : integer, random_state, or None (default) Indicator of random number generation state. See :ref:`Randomness`. Returns ------- G : A random graph containing no path on four vertices. See Also -------- full_join union References ---------- .. [1] D.G. Corneil, H. Lerchs, L.Stewart Burlingham, "Complement reducible graphs", Discrete Applied Mathematics, Volume 3, Issue 3, 1981, Pages 163-174, ISSN 0166-218X. rcs |tˆƒS)N)Úlen)Úx©ÚR©ú@/tmp/pip-unpacked-wheel-_lngutwb/networkx/generators/cographs.pyÚ;óz random_cograph..r)ÚnxZ empty_graphÚrangeZ relabel_nodesÚcopyÚrandintZ full_joinZdisjoint_union)ÚnÚseedÚiZRRr rr rs$  )N)Ú__doc__Znetworkxr Znetworkx.utilsrÚ__all__rr r r r Ús