chore: import upstream snapshot with attribution

2026-07-13 12:36:30 +08:00
commit 55ab4e4a73
473 changed files with 72932 additions and 0 deletions
@@ -0,0 +1,109 @@
+import easygraph as eg
+import easygraph.functions.path
+
+from easygraph.utils.decorators import *
+
+__all__ = ["diameter", "eccentricity"]
+
+@hybrid("cpp_eccentricity")
+def eccentricity(G, v=None, sp=None):
+    """Returns the eccentricity of nodes in G.
+
+    The eccentricity of a node v is the maximum distance from v to
+    all other nodes in G.
+
+    Parameters
+    ----------
+    G : EasyGraph graph
+       A graph
+
+    v : node, optional
+       Return value of specified node
+
+    sp : dict of dicts, optional
+       All pairs shortest path lengths as a dictionary of dictionaries
+
+    Returns
+    -------
+    ecc : dictionary
+       A dictionary of eccentricity values keyed by node.
+
+    Examples
+    --------
+    >>> G = eg.Graph([(1, 2), (1, 3), (1, 4), (3, 4), (3, 5), (4, 5)])
+    >>> dict(eg.eccentricity(G))
+    {1: 2, 2: 3, 3: 2, 4: 2, 5: 3}
+
+    >>> dict(eg.eccentricity(G, v=[1, 5]))  # This returns the eccentrity of node 1 & 5
+    {1: 2, 5: 3}
+
+    """
+    #    if v is None:                # none, use entire graph
+    #        nodes=G.nodes()
+    #    elif v in G:               # is v a single node
+    #        nodes=[v]
+    #    else:                      # assume v is a container of nodes
+    #        nodes=v
+    order = G.order()
+
+    e = {}
+    for n in G.nbunch_iter(v):
+        if sp is None:
+            length = eg.single_source_dijkstra(G, n)
+            L = len(length)
+        else:
+            try:
+                length = sp[n]
+                L = len(length)
+            except TypeError as err:
+                raise eg.EasyGraphError('Format of "sp" is invalid.') from err
+        if L != order:
+            if G.is_directed():
+                msg = (
+                    "Found infinite path length because the digraph is not"
+                    " strongly connected"
+                )
+            else:
+                msg = "Found infinite path length because the graph is not connected"
+            raise eg.EasyGraphError(msg)
+
+        e[n] = max(length.values())
+
+    if v in G:
+        return e[v]  # return single value
+    else:
+        return e
+
+
+def diameter(G, e=None):
+    """Returns the diameter of the graph G.
+
+    The diameter is the maximum eccentricity.
+
+    Parameters
+    ----------
+    G : EasyGraph graph
+       A graph
+
+    e : eccentricity dictionary, optional
+      A precomputed dictionary of eccentricities.
+
+    Returns
+    -------
+    d : integer
+       Diameter of graph
+
+    Examples
+    --------
+    >>> G = eg.Graph([(1, 2), (1, 3), (1, 4), (3, 4), (3, 5), (4, 5)])
+    >>> eg.diameter(G)
+    3
+
+    See Also
+    --------
+    eccentricity
+    """
+
+    if e is None:
+        e = eccentricity(G)
+    return max(e.values())