add python tests for Leiden numbering

python/cugraph/cugraph/tests/community/test_leiden.py

@@ -1,4 +1,4 @@
-# Copyright (c) 2019-2024, NVIDIA CORPORATION.
+# Copyright (c) 2019-2025, 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
@@ -19,6 +19,7 @@
 
 import cugraph
 import cudf
+from cudf.testing.testing import assert_series_equal
 from cugraph.testing import utils, UNDIRECTED_DATASETS
 from cugraph.datasets import karate_asymmetric
 
@@ -185,6 +186,15 @@ def test_leiden(graph_file):
     leiden_parts, leiden_mod = cugraph_leiden(G)
     louvain_parts, louvain_mod = cugraph_louvain(G)
 
+    unique_parts = leiden_parts["partition"].drop_duplicates().sort_values(
+        ascending=True).reset_index(drop=True)
+
+    idx_col = cudf.Series(unique_parts.index)
+
+    # Ensure Leiden cluster's ID are numbered consecutively
+    assert_series_equal(
+        unique_parts, idx_col, check_dtype=False, check_names=False)
+
     # Leiden modularity score is smaller than Louvain's
     assert leiden_mod >= (0.75 * louvain_mod)
 
@@ -202,6 +212,15 @@ def test_leiden_nx(graph_file):
     leiden_parts, leiden_mod = cugraph_leiden(G)
     louvain_parts, louvain_mod = cugraph_louvain(G)
 
+    unique_parts = cudf.Series(leiden_parts.values()).drop_duplicates().sort_values(
+        ascending=True).reset_index(drop=True)
+
+    idx_col = cudf.Series(unique_parts.index)
+
+    # Ensure Leiden cluster's ID are numbered consecutively
+    assert_series_equal(
+        unique_parts, idx_col, check_dtype=False, check_names=False)
+
     # Calculating modularity scores for comparison
     # Leiden modularity score is smaller than Louvain's
     assert leiden_mod >= (0.75 * louvain_mod)

python/cugraph/cugraph/tests/community/test_leiden_mg.py

@@ -1,4 +1,4 @@
-# Copyright (c) 2020-2024, NVIDIA CORPORATION.
+# Copyright (c) 2020-2025, 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
@@ -16,6 +16,8 @@
 import cugraph
 import cugraph.dask as dcg
 from cugraph.datasets import karate_asymmetric, karate, dolphins
+import cudf
+from cudf.testing.testing import assert_series_equal
 
 
 # =============================================================================
@@ -64,6 +66,15 @@ def test_mg_leiden_with_edgevals_undirected_graph(dask_client, dataset):
     dg = get_mg_graph(dataset, directed=False)
     parts, mod = dcg.leiden(dg)
 
+    unique_parts = parts["partition"].compute().drop_duplicates().sort_values(
+        ascending=True).reset_index(drop=True)
+
+    idx_col = cudf.Series(unique_parts.index)
+
+    # Ensure Leiden cluster's ID are numbered consecutively
+    assert_series_equal(
+        unique_parts, idx_col, check_dtype=False, check_names=False)
+
     # FIXME: either call Nx with the same dataset and compare results, or
     # hardcode golden results to compare to.
     print()