--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/planemo/lib/python3.7/site-packages/networkx/algorithms/wiener.py	Fri Jul 31 00:32:28 2020 -0400
@@ -0,0 +1,85 @@
+# wiener.py - functions related to the Wiener index of a graph
+#
+# Copyright 2015 NetworkX developers.
+#
+# This file is part of NetworkX.
+#
+# NetworkX is distributed under a BSD license; see LICENSE.txt for more
+# information.
+"""Functions related to the Wiener index of a graph."""
+
+from itertools import chain
+
+from .components import is_connected
+from .components import is_strongly_connected
+from .shortest_paths import shortest_path_length as spl
+
+__all__ = ['wiener_index']
+
+#: Rename the :func:`chain.from_iterable` function for the sake of
+#: brevity.
+chaini = chain.from_iterable
+
+
+def wiener_index(G, weight=None):
+    """Returns the Wiener index of the given graph.
+
+    The *Wiener index* of a graph is the sum of the shortest-path
+    distances between each pair of reachable nodes. For pairs of nodes
+    in undirected graphs, only one orientation of the pair is counted.
+
+    Parameters
+    ----------
+    G : NetworkX graph
+
+    weight : object
+        The edge attribute to use as distance when computing
+        shortest-path distances. This is passed directly to the
+        :func:`networkx.shortest_path_length` function.
+
+    Returns
+    -------
+    float
+        The Wiener index of the graph `G`.
+
+    Raises
+    ------
+    NetworkXError
+        If the graph `G` is not connected.
+
+    Notes
+    -----
+    If a pair of nodes is not reachable, the distance is assumed to be
+    infinity. This means that for graphs that are not
+    strongly-connected, this function returns ``inf``.
+
+    The Wiener index is not usually defined for directed graphs, however
+    this function uses the natural generalization of the Wiener index to
+    directed graphs.
+
+    Examples
+    --------
+    The Wiener index of the (unweighted) complete graph on *n* nodes
+    equals the number of pairs of the *n* nodes, since each pair of
+    nodes is at distance one::
+
+        >>> import networkx as nx
+        >>> n = 10
+        >>> G = nx.complete_graph(n)
+        >>> nx.wiener_index(G) == n * (n - 1) / 2
+        True
+
+    Graphs that are not strongly-connected have infinite Wiener index::
+
+        >>> G = nx.empty_graph(2)
+        >>> nx.wiener_index(G)
+        inf
+
+    """
+    is_directed = G.is_directed()
+    if (is_directed and not is_strongly_connected(G)) or \
+            (not is_directed and not is_connected(G)):
+        return float('inf')
+    total = sum(chaini(p.values() for v, p in spl(G, weight=weight)))
+    # Need to account for double counting pairs of nodes in undirected graphs.
+    return total if is_directed else total / 2