
    wg                     J    d Z ddlZdgZ ej                  d      dd       Zy)z
Flow Hierarchy.
    Nflow_hierarchyweight)
edge_attrsc                 "    t        j                         rt        j                  d       j                         st        j                  d      t        j                         }dt         fd|D               j                        z  z
  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 : string, optional (default=None)
       Attribute to use for edge weights. If None the weight defaults to 1.

    Returns
    -------
    h : float
       Flow hierarchy value

    Raises
    ------
    NetworkXError
       If `G` is not a directed graph or if `G` has no edges.

    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-flow_hierarchy not applicable to empty graphsz%G must be a digraph in flow_hierarchy   c              3   ^   K   | ]$  }j                  |      j                         & y wN)subgraphsize).0cGr   s     b/home/mcse/projects/flask/flask-venv/lib/python3.12/site-packages/networkx/algorithms/hierarchy.py	<genexpr>z!flow_hierarchy.<locals>.<genexpr>9   s$     ;!1::a=%%f-;s   *-)nxis_emptyNetworkXErroris_directedstrongly_connected_componentssumr   )r   r   sccs   `` r   r   r   
   sq    T 
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