Fix to_numeric not preserving Series index and name (#14718)

closes #14717

Authors:
  - Matthew Roeschke (https://github.com/mroeschke)

Approvers:
  - Bradley Dice (https://github.com/bdice)

URL: #14718

python/cudf/cudf/core/tools/numeric.py

@@ -1,4 +1,4 @@
-# Copyright (c) 2018-2023, NVIDIA CORPORATION.
+# Copyright (c) 2018-2024, NVIDIA CORPORATION.
 
 import warnings
 
@@ -161,7 +161,7 @@ def to_numeric(arg, errors="raise", downcast=None):
                     break
 
     if isinstance(arg, (cudf.Series, pd.Series)):
-        return cudf.Series(col)
+        return cudf.Series(col, index=arg.index, name=arg.name)
     else:
         if col.has_nulls():
             # To match pandas, always return a floating type filled with nan.

python/cudf/cudf/tests/test_numerical.py

@@ -1,4 +1,4 @@
-# Copyright (c) 2021-2023, NVIDIA CORPORATION.
+# Copyright (c) 2021-2024, NVIDIA CORPORATION.
 
 import numpy as np
 import pandas as pd
@@ -425,3 +425,11 @@ def test_series_to_numeric_bool(data, downcast):
     got = cudf.to_numeric(gs, downcast=downcast)
 
     assert_eq(expect, got)
+
+
+@pytest.mark.parametrize("klass", [cudf.Series, pd.Series])
+def test_series_to_numeric_preserve_index_name(klass):
+    ser = klass(["1"] * 8, index=range(2, 10), name="name")
+    result = cudf.to_numeric(ser)
+    expected = cudf.Series([1] * 8, index=range(2, 10), name="name")
+    assert_eq(result, expected)