Fix name selection in Index.difference and Index.intersection (#…

…13986)

closes #13985
This PR fixes issues with `Index.difference` and `Index.intersection` API where the name selection was incorrect and `NA` values handling wasn't happening in these two APIs.

Authors:
  - GALI PREM SAGAR (https://github.com/galipremsagar)

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

URL: #13986

python/cudf/cudf/core/_base_index.py

@@ -651,7 +651,7 @@ def _get_reconciled_name_object(self, other):
         case make a shallow copy of self.
         """
         name = _get_result_name(self.name, other.name)
-        if self.name != name:
+        if not _is_same_name(self.name, name):
             return self.rename(name)
         return self
 
@@ -943,24 +943,27 @@ def difference(self, other, sort=None):
 
         other = cudf.Index(other)
 
+        res_name = _get_result_name(self.name, other.name)
+
         if is_mixed_with_object_dtype(self, other):
             difference = self.copy()
         else:
             other = other.copy(deep=False)
-            other.names = self.names
             difference = cudf.core.index._index_from_data(
-                cudf.DataFrame._from_data(self._data)
+                cudf.DataFrame._from_data({"None": self._column})
                 .merge(
-                    cudf.DataFrame._from_data(other._data),
+                    cudf.DataFrame._from_data({"None": other._column}),
                     how="leftanti",
-                    on=self.name,
+                    on="None",
                 )
                 ._data
             )
 
             if self.dtype != other.dtype:
                 difference = difference.astype(self.dtype)
 
+        difference.name = res_name
+
         if sort is None and len(other):
             return difference.sort_values()
 
@@ -1323,14 +1326,12 @@ def _union(self, other, sort=None):
         return union_result
 
     def _intersection(self, other, sort=None):
-        other_unique = other.unique()
-        other_unique.names = self.names
         intersection_result = cudf.core.index._index_from_data(
-            cudf.DataFrame._from_data(self.unique()._data)
+            cudf.DataFrame._from_data({"None": self.unique()._column})
             .merge(
-                cudf.DataFrame._from_data(other_unique._data),
+                cudf.DataFrame._from_data({"None": other.unique()._column}),
                 how="inner",
-                on=self.name,
+                on="None",
             )
             ._data
         )

python/cudf/cudf/tests/test_index.py

@@ -804,12 +804,16 @@ def test_index_to_series(data):
     ],
 )
 @pytest.mark.parametrize("sort", [None, False])
-def test_index_difference(data, other, sort):
-    pd_data = pd.Index(data)
-    pd_other = pd.Index(other)
+@pytest.mark.parametrize(
+    "name_data,name_other",
+    [("abc", "c"), (None, "abc"), ("abc", pd.NA), ("abc", "abc")],
+)
+def test_index_difference(data, other, sort, name_data, name_other):
+    pd_data = pd.Index(data, name=name_data)
+    pd_other = pd.Index(other, name=name_other)
 
-    gd_data = cudf.core.index.as_index(data)
-    gd_other = cudf.core.index.as_index(other)
+    gd_data = cudf.from_pandas(pd_data)
+    gd_other = cudf.from_pandas(pd_other)
 
     expected = pd_data.difference(pd_other, sort=sort)
     actual = gd_data.difference(gd_other, sort=sort)
@@ -2066,7 +2070,7 @@ def test_union_index(idx1, idx2, sort):
         (pd.RangeIndex(0, 10), pd.RangeIndex(3, 7)),
         (pd.RangeIndex(0, 10), pd.RangeIndex(-10, 20)),
         (pd.RangeIndex(0, 10, name="a"), pd.RangeIndex(90, 100, name="b")),
-        (pd.Index([0, 1, 2, 30], name="a"), pd.Index([30, 0, 90, 100])),
+        (pd.Index([0, 1, 2, 30], name=pd.NA), pd.Index([30, 0, 90, 100])),
         (pd.Index([0, 1, 2, 30], name="a"), [90, 100]),
         (pd.Index([0, 1, 2, 30]), pd.Index([0, 10, 1.0, 11])),
         (pd.Index(["a", "b", "c", "d", "c"]), pd.Index(["a", "c", "z"])),