Raise if nx input and copy=False

python/nx-cugraph/nx_cugraph/algorithms/operators/unary.py

@@ -51,5 +51,10 @@ def reverse(G, copy=True):
     if not G.is_directed():
         raise nx.NetworkXError("Cannot reverse an undirected graph.")
     if isinstance(G, nx.Graph):
+        if not copy:
+            raise RuntimeError(
+                "Using `copy=False` is invalid when using a NetworkX graph "
+                "as input to `nx_cugraph.reverse`"
+            )
         G = nxcg.from_networkx(G, preserve_all_attrs=True)
     return G.reverse(copy=copy)

python/nx-cugraph/nx_cugraph/relabel.py

@@ -30,6 +30,11 @@
 @networkx_algorithm(version_added="24.08")
 def relabel_nodes(G, mapping, copy=True):
     if isinstance(G, nx.Graph):
+        if not copy:
+            raise RuntimeError(
+                "Using `copy=False` is invalid when using a NetworkX graph "
+                "as input to `nx_cugraph.relabel_nodes`"
+            )
         G = nxcg.from_networkx(G, preserve_all_attrs=True)
     it = range(G._N) if G.key_to_id is None else G.id_to_key
     if callable(mapping):

python/nx-cugraph/nx_cugraph/tests/test_relabel.py

@@ -52,3 +52,12 @@ def test_relabel_multigraph(create_using):
     Hnx = nx.relabel_nodes(G, {2: 3, 1: 3, 0: 3})
     Hcg = nxcg.relabel_nodes(G, {2: 3, 1: 3, 0: 3})
     assert_graphs_equal(Hnx, Hcg)
+
+
+def test_relabel_nx_input():
+    G = nx.complete_graph(3)
+    with pytest.raises(RuntimeError, match="Using `copy=False` is invalid"):
+        nxcg.relabel_nodes(G, {0: 1}, copy=False)
+    Hnx = nx.relabel_nodes(G, {0: 1}, copy=True)
+    Hcg = nxcg.relabel_nodes(G, {0: 1}, copy=True)
+    assert_graphs_equal(Hnx, Hcg)