fix tests

doc/source/whatsnew/v3.0.0.rst

@@ -504,7 +504,7 @@ Timezones
 Numeric
 ^^^^^^^
 - Bug in ``np.matmul`` with :class:`Index` inputs raising a ``TypeError`` (:issue:`57079`)
--
+- Bug in :meth:`DataFrame.quantile` where the column type was not preserved when ``numeric_only=True`` with a list-like ``q`` produced an empty result (:issue:`?``)
 
 Conversion
 ^^^^^^^^^^

pandas/core/methods/selectn.py

@@ -29,6 +29,8 @@
 )
 from pandas.core.dtypes.dtypes import BaseMaskedDtype
 
+from pandas.core.indexes.api import default_index
+
 if TYPE_CHECKING:
     from pandas._typing import (
         DtypeObj,
@@ -38,6 +40,7 @@
 
     from pandas import (
         DataFrame,
+        Index,
         Series,
     )
 else:
@@ -199,11 +202,6 @@ def __init__(self, obj: DataFrame, n: int, keep: str, columns: IndexLabel) -> No
         self.columns = columns
 
     def compute(self, method: str) -> DataFrame:
-        from pandas.core.api import (
-            Index,
-            default_index,
-        )
-
         n = self.n
         frame = self.obj
         columns = self.columns

pandas/tests/frame/methods/test_quantile.py

@@ -710,14 +710,14 @@ def test_quantile_empty_no_columns(self, interp_method):
         result = df.quantile(
             0.5, numeric_only=True, interpolation=interpolation, method=method
         )
-        expected = Series([], index=[], name=0.5, dtype=np.float64)
+        expected = Series([], name=0.5, dtype=np.float64)
         expected.index.name = "captain tightpants"
         tm.assert_series_equal(result, expected)
 
         result = df.quantile(
             [0.5], numeric_only=True, interpolation=interpolation, method=method
         )
-        expected = DataFrame([], index=[0.5], columns=[])
+        expected = DataFrame([], index=[0.5])
         expected.columns.name = "captain tightpants"
         tm.assert_frame_equal(result, expected)
 

pandas/tests/generic/test_generic.py

@@ -93,15 +93,19 @@ def test_get_numeric_data(self, frame_or_series):
         if isinstance(o, DataFrame):
             # preserve columns dtype
             expected.columns = o.columns[:0]
-        # https://github.com/pandas-dev/pandas/issues/50862
-        tm.assert_equal(result.reset_index(drop=True), expected)
+        tm.assert_equal(result, expected)
 
         # get the bool data
         arr = np.array([True, True, False, True])
         o = construct(frame_or_series, n, value=arr, **kwargs)
         result = o._get_numeric_data()
         tm.assert_equal(result, o)
 
+    def test_get_bool_data_empty_preserve_index(self):
+        expected = Series([], dtype="bool")
+        result = expected._get_bool_data()
+        tm.assert_series_equal(result, expected, check_index_type=True)
+
     def test_nonzero(self, frame_or_series):
         # GH 4633
         # look at the boolean/nonzero behavior for objects

pandas/tests/indexes/test_base.py

@@ -1558,7 +1558,7 @@ def test_ensure_index_uint64(self):
 
     def test_get_combined_index(self):
         result = _get_combined_index([])
-        expected = Index([])
+        expected = RangeIndex(0)
         tm.assert_index_equal(result, expected)
 
 

pandas/tests/series/methods/test_get_numeric_data.py

@@ -1,5 +1,4 @@
 from pandas import (
-    Index,
     Series,
     date_range,
 )
@@ -19,7 +18,7 @@ def test_get_numeric_data_preserve_dtype(self):
 
         obj = Series([1, "2", 3.0])
         result = obj._get_numeric_data()
-        expected = Series([], dtype=object, index=Index([], dtype=object))
+        expected = Series([], dtype=object)
         tm.assert_series_equal(result, expected)
 
         obj = Series([True, False, True])
@@ -28,5 +27,5 @@ def test_get_numeric_data_preserve_dtype(self):
 
         obj = Series(date_range("20130101", periods=3))
         result = obj._get_numeric_data()
-        expected = Series([], dtype="M8[ns]", index=Index([], dtype=object))
+        expected = Series([], dtype="M8[ns]")
         tm.assert_series_equal(result, expected)