U 9v fÞã@s dZddlZdgZddd„ZdS)z Flow Hierarchy. éNÚflow_hierarchycsBˆ ¡st d¡‚t ˆ¡}dt‡‡fdd„|Dƒƒˆ ˆ¡S)a‚Returns the flow hierarchy of a directed network. Flow hierarchy is defined as the fraction of edges not participating in cycles in a directed graph [1]_. Parameters ---------- G : DiGraph or MultiDiGraph A directed graph weight : key,optional (default=None) Attribute to use for node weights. If None the weight defaults to 1. Returns ------- h : float Flow hierarchy value Notes ----- The algorithm described in [1]_ computes the flow hierarchy through exponentiation of the adjacency matrix. This function implements an alternative approach that finds strongly connected components. An edge is in a cycle if and only if it is in a strongly connected component, which can be found in $O(m)$ time using Tarjan's algorithm. References ---------- .. [1] Luo, J.; Magee, C.L. (2011), Detecting evolving patterns of self-organizing networks by flow hierarchy measurement, Complexity, Volume 16 Issue 6 53-61. DOI: 10.1002/cplx.20368 http://web.mit.edu/~cmagee/www/documents/28-DetectingEvolvingPatterns_FlowHierarchy.pdf z%G must be a digraph in flow_hierarchyéc3s|]}ˆ |¡ ˆ¡VqdS)N)ZsubgraphÚsize)Ú.0Úc©ÚGÚweight©úA/tmp/pip-unpacked-wheel-_lngutwb/networkx/algorithms/hierarchy.pyÚ /sz!flow_hierarchy..)Z is_directedÚnxZ NetworkXErrorZstrongly_connected_componentsÚsumr)rr Zsccr rr r s#  )N)Ú__doc__Znetworkxr Ú__all__rr r r r Ús