Enable sort=True for Index.union, Index.difference and `Index.i…

…ntersection` (#13497)

This PR enables `sort=True` for `union`, `difference`, and `intersection` APIs in `Index`. 

This also fixes 1 pytest failure and adds 77 pytests:
On `Index_sort_2.0`:
```
= 230 failed, 95836 passed, 2045 skipped, 768 xfailed, 308 xpassed in 438.88s (0:07:18) =
```
On `pandas_2.0_feature_branch`:
```
= 231 failed, 95767 passed, 2045 skipped, 764 xfailed, 300 xpassed in 432.59s (0:07:12) =
```

xref: pandas-dev/pandas#25151

python/cudf/cudf/core/_base_index.py

@@ -334,6 +334,7 @@ def union(self, other, sort=None):
               2. `self` or `other` has length 0.
 
             * False : do not sort the result.
+            * True : Sort the result (which may raise TypeError).
 
         Returns
         -------
@@ -395,10 +396,10 @@ def union(self, other, sort=None):
         if not isinstance(other, BaseIndex):
             other = cudf.Index(other, name=self.name)
 
-        if sort not in {None, False}:
+        if sort not in {None, False, True}:
             raise ValueError(
                 f"The 'sort' keyword only takes the values of "
-                f"None or False; {sort} was passed."
+                f"[None, False, True]; {sort} was passed."
             )
 
         if not len(other) or self.equals(other):
@@ -425,6 +426,7 @@ def intersection(self, other, sort=False):
             * False : do not sort the result.
             * None : sort the result, except when `self` and `other` are equal
               or when the values cannot be compared.
+            * True : Sort the result (which may raise TypeError).
 
         Returns
         -------
@@ -475,10 +477,10 @@ def intersection(self, other, sort=False):
         if not isinstance(other, BaseIndex):
             other = cudf.Index(other, name=self.name)
 
-        if sort not in {None, False}:
+        if sort not in {None, False, True}:
             raise ValueError(
                 f"The 'sort' keyword only takes the values of "
-                f"None or False; {sort} was passed."
+                f"[None, False, True]; {sort} was passed."
             )
 
         if self.equals(other):
@@ -768,6 +770,7 @@ def difference(self, other, sort=None):
             * None : Attempt to sort the result, but catch any TypeErrors
               from comparing incomparable elements.
             * False : Do not sort the result.
+            * True : Sort the result (which may raise TypeError).
 
         Returns
         -------
@@ -787,16 +790,18 @@ def difference(self, other, sort=None):
         >>> idx1.difference(idx2, sort=False)
         Index([2, 1], dtype='int64')
         """
-        if sort not in {None, False}:
+        if sort not in {None, False, True}:
             raise ValueError(
                 f"The 'sort' keyword only takes the values "
-                f"of None or False; {sort} was passed."
+                f"of [None, False, True]; {sort} was passed."
             )
 
         other = cudf.Index(other)
 
-        if is_mixed_with_object_dtype(self, other):
+        if is_mixed_with_object_dtype(self, other) or len(other) == 0:
             difference = self.copy()
+            if sort is True:
+                return difference.sort_values()
         else:
             other = other.copy(deep=False)
             other.names = self.names
@@ -813,7 +818,7 @@ def difference(self, other, sort=None):
             if self.dtype != other.dtype:
                 difference = difference.astype(self.dtype)
 
-        if sort is None and len(other):
+        if sort in {None, True} and len(other):
             return difference.sort_values()
 
         return difference
@@ -1170,7 +1175,7 @@ def _union(self, other, sort=None):
         )
         union_result = cudf.core.index._index_from_data({0: res._data[0]})
 
-        if sort is None and len(other):
+        if sort in {None, True} and len(other):
             return union_result.sort_values()
         return union_result
 
@@ -1187,7 +1192,7 @@ def _intersection(self, other, sort=None):
             ._data
         )
 
-        if sort is None and len(other):
+        if sort is {None, True} and len(other):
             return intersection_result.sort_values()
         return intersection_result
 

python/cudf/cudf/core/index.py

@@ -699,7 +699,7 @@ def _union(self, other, sort=None):
             ):
                 result = type(self)(start_r, end_r + step_s / 2, step_s / 2)
             if result is not None:
-                if sort is None and not result.is_monotonic_increasing:
+                if sort in {None, True} and not result.is_monotonic_increasing:
                     return result.sort_values()
                 else:
                     return result
@@ -710,7 +710,7 @@ def _union(self, other, sort=None):
         return self._as_int_index()._union(other, sort=sort)
 
     @_cudf_nvtx_annotate
-    def _intersection(self, other, sort=False):
+    def _intersection(self, other, sort=None):
         if not isinstance(other, RangeIndex):
             return super()._intersection(other, sort=sort)
 
@@ -750,7 +750,7 @@ def _intersection(self, other, sort=False):
 
         if (self.step < 0 and other.step < 0) is not (new_index.step < 0):
             new_index = new_index[::-1]
-        if sort is None:
+        if sort in {None, True}:
             new_index = new_index.sort_values()
 
         return new_index

python/cudf/cudf/core/multiindex.py

@@ -1796,7 +1796,7 @@ def _union(self, other, sort=None):
 
         midx = MultiIndex.from_frame(result_df.iloc[:, : self.nlevels])
         midx.names = self.names if self.names == other.names else None
-        if sort is None and len(other):
+        if sort in {None, True} and len(other):
             return midx.sort_values()
         return midx
 
@@ -1819,7 +1819,7 @@ def _intersection(self, other, sort=None):
 
         result_df = cudf.merge(self_df, other_df, how="inner")
         midx = self.__class__.from_frame(result_df, names=res_name)
-        if sort is None and len(other):
+        if sort in {None, True} and len(other):
             return midx.sort_values()
         return midx
 

python/cudf/cudf/tests/test_index.py

@@ -781,7 +781,7 @@ def test_index_to_series(data):
         [],
     ],
 )
-@pytest.mark.parametrize("sort", [None, False])
+@pytest.mark.parametrize("sort", [None, False, True])
 def test_index_difference(data, other, sort):
     pd_data = pd.Index(data)
     pd_other = pd.Index(other)
@@ -801,8 +801,8 @@ def test_index_difference_sort_error():
     assert_exceptions_equal(
         pdi.difference,
         gdi.difference,
-        ([pdi], {"sort": True}),
-        ([gdi], {"sort": True}),
+        ([pdi], {"sort": "A"}),
+        ([gdi], {"sort": "A"}),
     )
 
 
@@ -2236,21 +2236,53 @@ def test_range_index_concat(objs):
     [
         (pd.RangeIndex(0, 10), pd.RangeIndex(3, 7)),
         (pd.RangeIndex(0, 10), pd.RangeIndex(10, 20)),
-        (pd.RangeIndex(0, 10, 2), pd.RangeIndex(1, 5, 3)),
-        (pd.RangeIndex(1, 5, 3), pd.RangeIndex(0, 10, 2)),
-        (pd.RangeIndex(1, 10, 3), pd.RangeIndex(1, 5, 2)),
+        pytest.param(
+            pd.RangeIndex(0, 10, 2),
+            pd.RangeIndex(1, 5, 3),
+            marks=pytest.mark.xfail(
+                condition=PANDAS_GE_200,
+                reason="https://github.com/pandas-dev/pandas/issues/53490",
+                strict=False,
+            ),
+        ),
+        pytest.param(
+            pd.RangeIndex(1, 5, 3),
+            pd.RangeIndex(0, 10, 2),
+            marks=pytest.mark.xfail(
+                condition=PANDAS_GE_200,
+                reason="https://github.com/pandas-dev/pandas/issues/53490",
+                strict=False,
+            ),
+        ),
+        pytest.param(
+            pd.RangeIndex(1, 10, 3),
+            pd.RangeIndex(1, 5, 2),
+            marks=pytest.mark.xfail(
+                condition=PANDAS_GE_200,
+                reason="https://github.com/pandas-dev/pandas/issues/53490",
+                strict=False,
+            ),
+        ),
         (pd.RangeIndex(1, 5, 2), pd.RangeIndex(1, 10, 3)),
         (pd.RangeIndex(1, 100, 3), pd.RangeIndex(1, 50, 3)),
         (pd.RangeIndex(1, 100, 3), pd.RangeIndex(1, 50, 6)),
-        (pd.RangeIndex(1, 100, 6), pd.RangeIndex(1, 50, 3)),
+        pytest.param(
+            pd.RangeIndex(1, 100, 6),
+            pd.RangeIndex(1, 50, 3),
+            marks=pytest.mark.xfail(
+                condition=PANDAS_GE_200,
+                reason="https://github.com/pandas-dev/pandas/issues/53490",
+                strict=False,
+            ),
+        ),
         (pd.RangeIndex(0, 10, name="a"), pd.RangeIndex(90, 100, name="b")),
         (pd.Index([0, 1, 2, 30], name="a"), pd.Index([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"])),
     ],
 )
-@pytest.mark.parametrize("sort", [None, False])
+@pytest.mark.parametrize("sort", [None, False, True])
 def test_union_index(idx1, idx2, sort):
     expected = idx1.union(idx2, sort=sort)
 
@@ -2280,7 +2312,7 @@ def test_union_index(idx1, idx2, sort):
         (pd.Index([True, False, True, True]), pd.Index([True, True])),
     ],
 )
-@pytest.mark.parametrize("sort", [None, False])
+@pytest.mark.parametrize("sort", [None, False, True])
 def test_intersection_index(idx1, idx2, sort):
 
     expected = idx1.intersection(idx2, sort=sort)