3 Md@sddZddlZddlmZddlmZmZmZddl m Z dgZ ddZ ed ed dd dZ dS)uBFunctions for computing the Kernighan–Lin bipartition algorithm.N)count)not_implemented_forpy_random_state BinaryHeap) is_partitionkernighan_lin_bisectionc #sttf\}}xLttD]:\}}}tfdd|D}|j||rV|n| q$Wfdd}d} } xT|r|r|j\}}||||j\} } ||| | || 7} | | || ffVq|WdS)z This is a modified form of Kernighan-Lin, which moves single nodes at a time, alternating between sides to keep the bisection balanced. We keep two min-heaps of swap costs to make optimal-next-move selection fast. c3s$|]\}}|r|n| VqdS)N).0vw)sider]/var/www/html/virt/lib/python3.6/site-packages/networkx/algorithms/community/kernighan_lin.py sz'_kernighan_lin_sweep..cs`xZ|D]N\}}|}|j|}|dk r |d||krB| n|7}|j||dq WdS)NT)getinsert)Zcosts_xxyr Zcosts_yZcost_y)costsedgesr rr _update_costss   z+_kernighan_lin_sweep.._update_costsrN)rziprsumrpop) rr Zcosts0Zcosts1uZside_uZedges_uZcost_uriZtotcostr Zcost_vr)rrr r _kernighan_lin_sweep s      rZdirected weightcst}t}|j|ddt|D|dkrVdg|ddg|dd}nxy |\}} Wn2ttfk r} ztjd| WYdd} ~ XnXt|| fstjddg|}x|D] } d|| <qWj rfd d |D} nfd d |D} xpt |D]d} tt | |}t |\}}}|dkr:Px4|d|dD] \}}\}}d||<d||<qLWqWd 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 ^sz+kernighan_lin_bisection..Nrrzpartition must be two setszpartition invalidcs(g|] }fdd|jDqS)cs2g|]*\}}|tfdd|jDfqS)c3s|]}|jdVqdS)r!N)r)r e)rrr rpsz@kernighan_lin_bisection....)rvalues)r rd)indexrrr psz6kernighan_lin_bisection...)items)r r )Gr%rrr r&osz+kernighan_lin_bisection..cs(g|] }fdd|jDqS)cs$g|]\}}||jdfqS)r!)r)r rr")r%rrr r&wsz6kernighan_lin_bisection...)r')r r )r(r%rrr r&wscSsh|]\}}|dkr|qS)rr)r rsrrr sz*kernighan_lin_bisection..cSsh|]\}}|dkr|qS)r!r)r rr)rrr r*s)lenlistshuffle enumerate TypeError ValueErrornxZ NetworkXErrorrZ is_multigraphrangerminr)r( partitionZmax_iterrseednlabelsr ABr"arrrZmin_costZmin_i_rr r)r(r%rr r(s<3 "        )NrrN)__doc__Znetworkxr1 itertoolsrZnetworkx.utilsrrrZ-networkx.algorithms.community.community_utilsr__all__rrrrrr s