U ?h@sddZddlmZddlZddlmZddlmZm Z m Z dgZ ddZ e d e d dd dZ dS)uBFunctions for computing the Kernighan–Lin bipartition algorithm.)countN) is_partition) BinaryHeapnot_implemented_forpy_random_statekernighan_lin_bisectionc #sttf\}}ttD]:\}}}tfdd|D}|||rT|n| q"fdd}d} d} |r|r|\}}||||\} } ||| | || 7} | d7} | | || ffVqvdS)z This is a modified form of Kernighan-Lin, which moves single nodes at a time, alternating between sides to keep the bisection balanced. We keep two min-heaps of swap costs to make optimal-next-move selection fast. c3s$|]\}}|r|n| VqdS)N).0vw)sider]/var/www/html/venv/lib/python3.8/site-packages/networkx/algorithms/community/kernighan_lin.py sz'_kernighan_lin_sweep..cs\|D]N\}}|}||}|dk r|d||kr@| n|7}|||dqdS)NT)getinsert)Zcosts_xxyr Zcosts_yZcost_ycostsedgesr rr _update_costss   z+_kernighan_lin_sweep.._update_costsrN)rziprsumrpop) rr Zcosts0Zcosts1uZside_uZedges_uZcost_uriZtotcostr Zcost_vrrr _kernighan_lin_sweep s     rZdirected weightc st}t}||ddt|D|dkrVdg|ddg|dd}nxz |\}} Wn2ttfk r} ztd| W5d} ~ XYnXt|| fstddg|}|D]} d|| <q rfd d |D} nfd d |D} t |D]`} tt | |}t |\}}}|dkr<qn|d|D] \}}\}}d||<d||<qHq d d t ||D}dd t ||D} || fS)uPartition a graph into two blocks using the Kernighan–Lin algorithm. This algorithm partitions a network into two sets by iteratively swapping pairs of nodes to reduce the edge cut between the two sets. The pairs are chosen according to a modified form of Kernighan-Lin, which moves node individually, alternating between sides to keep the bisection balanced. Parameters ---------- G : graph partition : tuple Pair of iterables containing an initial partition. If not specified, a random balanced partition is used. max_iter : int Maximum number of times to attempt swaps to find an improvemement before giving up. weight : key Edge data key to use as weight. If None, the weights are all set to one. seed : integer, random_state, or None (default) Indicator of random number generation state. See :ref:`Randomness`. Only used if partition is None Returns ------- partition : tuple A pair of sets of nodes representing the bipartition. Raises ------ NetworkXError If partition is not a valid partition of the nodes of the graph. References ---------- .. [1] Kernighan, B. W.; Lin, Shen (1970). "An efficient heuristic procedure for partitioning graphs." *Bell Systems Technical Journal* 49: 291--307. Oxford University Press 2011. cSsi|]\}}||qSrr)r rr rrr asz+kernighan_lin_bisection..Nrrrzpartition must be two setszpartition invalidcs(g|] }fdd|DqS)cs2g|]*\}}|tfdd|DfqS)c3s|]}|dVqdS)rNr)r e)r!rr rssz@kernighan_lin_bisection....)rvalues)r rdindexr!rr rs6kernighan_lin_bisection...itemsr r Gr(r!rr r)qs  z+kernighan_lin_bisection..cs(g|] }fdd|DqS)cs$g|]\}}||dfqSrr#)r rr$r'rr r)zsr*r+r-r.rr r)yscSsh|]\}}|dkr|qS)rrr rsrrr sz*kernighan_lin_bisection..cSsh|]\}}|dkr|qSr0rr1rrr r3s)lenlistshuffle enumerate TypeError ValueErrornxZ NetworkXErrorrZ is_multigraphrangerminr)r/ partitionZmax_iterr!seednlabelsr ABerrarrrZmin_costZmin_i_rr rr.r r+sB3 "     )Nr r!N)__doc__ itertoolsrZnetworkxr:Z-networkx.algorithms.community.community_utilsrZnetworkx.utilsrrr__all__rrrrrr s