Enforce matching type

cpp/src/c_api/random_walks.cpp

@@ -475,6 +475,14 @@ cugraph_error_code_t cugraph_node2vec(const cugraph_resource_handle_t* handle,
                                       cugraph_random_walk_result_t** result,
                                       cugraph_error_t** error)
 {
+  CAPI_EXPECTS(reinterpret_cast<cugraph::c_api::cugraph_graph_t*>(graph)->vertex_type_ ==
+                 reinterpret_cast<cugraph::c_api::cugraph_type_erased_device_array_view_t const*>(
+                   start_vertices)
+                   ->type_,
+               CUGRAPH_INVALID_INPUT,
+               "vertex type of graph and start_vertices must match",
+               *error);
+
   cugraph::c_api::node2vec_functor functor(
     handle, graph, start_vertices, max_length, compress_results, p, q);
 
@@ -528,6 +536,14 @@ cugraph_error_code_t cugraph_uniform_random_walks(
   cugraph_random_walk_result_t** result,
   cugraph_error_t** error)
 {
+  CAPI_EXPECTS(reinterpret_cast<cugraph::c_api::cugraph_graph_t*>(graph)->vertex_type_ ==
+                 reinterpret_cast<cugraph::c_api::cugraph_type_erased_device_array_view_t const*>(
+                   start_vertices)
+                   ->type_,
+               CUGRAPH_INVALID_INPUT,
+               "vertex type of graph and start_vertices must match",
+               *error);
+
   uniform_random_walks_functor functor(handle, graph, start_vertices, max_length);
 
   return cugraph::c_api::run_algorithm(graph, functor, result, error);
@@ -541,6 +557,14 @@ cugraph_error_code_t cugraph_biased_random_walks(
   cugraph_random_walk_result_t** result,
   cugraph_error_t** error)
 {
+  CAPI_EXPECTS(reinterpret_cast<cugraph::c_api::cugraph_graph_t*>(graph)->vertex_type_ ==
+                 reinterpret_cast<cugraph::c_api::cugraph_type_erased_device_array_view_t const*>(
+                   start_vertices)
+                   ->type_,
+               CUGRAPH_INVALID_INPUT,
+               "vertex type of graph and start_vertices must match",
+               *error);
+
   biased_random_walks_functor functor(handle, graph, start_vertices, max_length);
 
   return cugraph::c_api::run_algorithm(graph, functor, result, error);
@@ -556,6 +580,14 @@ cugraph_error_code_t cugraph_node2vec_random_walks(
   cugraph_random_walk_result_t** result,
   cugraph_error_t** error)
 {
+  CAPI_EXPECTS(reinterpret_cast<cugraph::c_api::cugraph_graph_t*>(graph)->vertex_type_ ==
+                 reinterpret_cast<cugraph::c_api::cugraph_type_erased_device_array_view_t const*>(
+                   start_vertices)
+                   ->type_,
+               CUGRAPH_INVALID_INPUT,
+               "vertex type of graph and start_vertices must match",
+               *error);
+
   node2vec_random_walks_functor functor(handle, graph, start_vertices, max_length, p, q);
 
   return cugraph::c_api::run_algorithm(graph, functor, result, error);

python/cugraph/cugraph/sampling/node2vec.py

@@ -1,4 +1,4 @@
-# Copyright (c) 2022-2023, NVIDIA CORPORATION.
+# Copyright (c) 2022-2024, 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
@@ -16,10 +16,32 @@
     node2vec as pylibcugraph_node2vec,
 )
 from cugraph.utilities import ensure_cugraph_obj_for_nx
+import warnings
 
 import cudf
 
 
+# FIXME: Move this function to the utility module so that it can be
+# shared by other algos
+def ensure_valid_dtype(input_graph, start_vertices):
+    vertex_dtype = input_graph.edgelist.edgelist_df.dtypes.iloc[0]
+    if isinstance(start_vertices, cudf.Series):
+        start_vertices_dtype = start_vertices.dtype
+    else:
+        start_vertices_dtype = start_vertices.dtypes.iloc[0]
+
+    if start_vertices_dtype != vertex_dtype:
+        warning_msg = (
+            "Node2vec requires 'start_vertices' to match the graph's "
+            f"'vertex' type. input graph's vertex type is: {vertex_dtype} and got "
+            f"'start_vertices' of type: {start_vertices_dtype}."
+        )
+        warnings.warn(warning_msg, UserWarning)
+        start_vertices = start_vertices.astype(vertex_dtype)
+
+    return start_vertices
+
+
 def node2vec(G, start_vertices, max_depth=1, compress_result=True, p=1.0, q=1.0):
     """
     Computes random walks for each node in 'start_vertices', under the
@@ -120,6 +142,8 @@ def node2vec(G, start_vertices, max_depth=1, compress_result=True, p=1.0, q=1.0)
         else:
             start_vertices = G.lookup_internal_vertex_id(start_vertices)
 
+    start_vertices = ensure_valid_dtype(G, start_vertices)
+
     vertex_set, edge_set, sizes = pylibcugraph_node2vec(
         resource_handle=ResourceHandle(),
         graph=G._plc_graph,

python/cugraph/cugraph/tests/sampling/test_node2vec.py

@@ -1,4 +1,4 @@
-# Copyright (c) 2022-2023, NVIDIA CORPORATION.
+# Copyright (c) 2022-2024, 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
@@ -27,6 +27,7 @@
 # =============================================================================
 DIRECTED_GRAPH_OPTIONS = [False, True]
 COMPRESSED = [False, True]
+START_VERTICES_TYPE = ["int32", "int64"]
 LINE = small_line
 KARATE = karate
 
@@ -150,11 +151,8 @@ def test_node2vec_line(graph_file, directed):
 @pytest.mark.parametrize(*_get_param_args("graph_file", SMALL_DATASETS))
 @pytest.mark.parametrize(*_get_param_args("directed", DIRECTED_GRAPH_OPTIONS))
 @pytest.mark.parametrize(*_get_param_args("compress", COMPRESSED))
-def test_node2vec(
-    graph_file,
-    directed,
-    compress,
-):
+@pytest.mark.parametrize(*_get_param_args("start_vertices_type", START_VERTICES_TYPE))
+def test_node2vec(graph_file, directed, compress, start_vertices_type):
     dataset_path = graph_file.get_path()
     cu_M = utils.read_csv_file(dataset_path)
 
@@ -165,8 +163,23 @@ def test_node2vec(
     )
     num_verts = G.number_of_vertices()
     k = random.randint(6, 12)
-    start_vertices = cudf.Series(random.sample(range(num_verts), k), dtype="int32")
+    # FIXME: Random sample can make it hard to debug
+    start_vertices = cudf.Series(
+        random.sample(range(num_verts), k), dtype=start_vertices_type
+    )
     max_depth = 5
+
+    if start_vertices_type == "int64":
+        warning_msg = (
+            "Node2vec requires 'start_vertices' to match the graph's "
+            "'vertex' type. input graph's vertex type is: int32 and "
+            "got 'start_vertices' of type: int64."
+        )
+        with pytest.warns(UserWarning, match=warning_msg):
+            calc_node2vec(
+                G, start_vertices, max_depth, compress_result=compress, p=0.8, q=0.5
+            )
+
     result, seeds = calc_node2vec(
         G, start_vertices, max_depth, compress_result=compress, p=0.8, q=0.5
     )