Handle BC normalization by adding docstring node and skipping test

Author: eriknw

_nx_cugraph/__init__.py

@@ -174,7 +174,7 @@
         "average_clustering": "Directed graphs and `weight` parameter are not yet supported.",
         "bellman_ford_path": "Negative cycles are not yet supported. ``NotImplementedError`` will be raised if there are negative edge weights. We plan to support negative edge weights soon. Also, callable ``weight`` argument is not supported.",
         "bellman_ford_path_length": "Negative cycles are not yet supported. ``NotImplementedError`` will be raised if there are negative edge weights. We plan to support negative edge weights soon. Also, callable ``weight`` argument is not supported.",
-        "betweenness_centrality": "`weight` parameter is not yet supported, and RNG with seed may be different.",
+        "betweenness_centrality": "`weight` parameter is not yet supported, and RNG with seed may be different. Normalization matches NetworkX version 3.5, which fixed normalization when using k (see https://github.com/networkx/networkx/pull/7908 for details).",
         "bfs_edges": "`sort_neighbors` parameter is not yet supported.",
         "bfs_predecessors": "`sort_neighbors` parameter is not yet supported.",
         "bfs_successors": "`sort_neighbors` parameter is not yet supported.",

nx_cugraph/algorithms/centrality/betweenness.py

@@ -14,21 +14,34 @@
 import pylibcugraph as plc
 from networkx.utils import create_py_random_state
 
+from nx_cugraph import _nxver
 from nx_cugraph.convert import _to_graph
 from nx_cugraph.utils import index_dtype, networkx_algorithm
 
 __all__ = ["betweenness_centrality", "edge_betweenness_centrality"]
 
 
+if _nxver < (3, 5):
+    EXTRA_DOCSTRING = (
+        " Normalization matches NetworkX version 3.5, which fixed normalization when "
+        "using k (see https://github.com/networkx/networkx/pull/7908 for details)."
+    )
+else:
+    EXTRA_DOCSTRING = ""
+
+
 @networkx_algorithm(
     is_incomplete=True,  # weight not supported
     version_added="23.10",
     _plc="betweenness_centrality",
+    docstring=(
+        "`weight` parameter is not yet supported, and RNG with seed may be different."
+        f"{EXTRA_DOCSTRING}"
+    ),
 )
 def betweenness_centrality(
     G, k=None, normalized=True, weight=None, endpoints=False, seed=None
 ):
-    """`weight` parameter is not yet supported, and RNG with seed may be different."""
     if weight is not None:
         raise NotImplementedError(
             "Weighted implementation of betweenness centrality not currently supported"

nx_cugraph/interface.py

@@ -1,4 +1,4 @@
-# Copyright (c) 2023-2024, NVIDIA CORPORATION.
+# Copyright (c) 2023-2025, NVIDIA CORPORATION.
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
 # You may obtain a copy of the License at
@@ -72,6 +72,8 @@ def key(testpath):
             "nx-cugraph Graph is incompatible in test setup in nx versions < 3.3"
         )
         different_iteration_order = "Different graph data iteration order"
+        # For nx version <= 3.4
+        bc_normalization_fixed = "BC normalization fixed in 3.5"
         # For all versions
         louvain_different = "Louvain may be different due to RNG"
         sssp_path_different = "sssp may choose a different valid path"
@@ -270,7 +272,15 @@ def key(testpath):
                     key("test_louvain.py:test_max_level"): louvain_different,
                 }
             )
-
+        if _nxver < (3, 5):
+            xfail.update(
+                {
+                    key(
+                        "test_betweenness_centrality.py:"
+                        "TestBetweennessCentrality.test_sample_from_P3"
+                    ): bc_normalization_fixed,
+                }
+            )
         xfail.update(
             {
                 key("test_louvain.py:test_karate_club_partition"): louvain_different,

nx_cugraph/utils/decorators.py

@@ -61,6 +61,8 @@ def __new__(
         extra_params: dict[str, str] | str | None = None,
         # Applies `nodes_or_number` decorator compatibly across versions (3.3 changed)
         nodes_or_number: list[int] | int | None = None,
+        # Alternative way to provide the docstring to add to the networkx docstring
+        docstring: str | None = None,
         # Metadata (for introspection only)
         version_added: str,  # Required
         is_incomplete: bool = False,  # See self.extra_doc for details if True
@@ -76,13 +78,16 @@ def __new__(
                 name=name,
                 extra_params=extra_params,
                 nodes_or_number=nodes_or_number,
+                docstring=docstring,
                 version_added=version_added,
                 is_incomplete=is_incomplete,
                 is_different=is_different,
                 fallback=fallback,
                 create_using_arg=create_using_arg,
                 _plc=_plc,
             )
+        if docstring:
+            func.__doc__ = docstring
         instance = object.__new__(cls)
         if nodes_or_number is not None and _nxver >= (3, 3):
             func = nx.utils.decorators.nodes_or_number(nodes_or_number)(func)