BUG: fix+test quantile with empty DataFrame, closes #23925

pandas/core/frame.py

@@ -8196,6 +8196,12 @@ def quantile(self, q=0.5, axis=0, numeric_only=True, interpolation="linear"):
         if is_transposed:
             data = data.T
 
+        if len(data.columns) == 0:
+            # GH#23925 _get_numeric_data may have dropped all columns
+            if is_list_like(q):
+                return self._constructor([], index=q, columns=[])
+            return self._constructor_sliced([], index=[], name=q)
+
         result = data._data.quantile(
             qs=q, axis=1, interpolation=interpolation, transposed=is_transposed
         )

pandas/tests/frame/test_quantile.py

@@ -439,7 +439,7 @@ def test_quantile_nat(self):
         )
         tm.assert_frame_equal(res, exp)
 
-    def test_quantile_empty(self):
+    def test_quantile_empty_no_rows(self):
 
         # floats
         df = DataFrame(columns=["a", "b"], dtype="float64")
@@ -467,3 +467,14 @@ def test_quantile_empty(self):
 
         # FIXME (gives NaNs instead of NaT in 0.18.1 or 0.19.0)
         # res = df.quantile(0.5, numeric_only=False)
+
+    def test_quantile_empty_no_columns(self):
+        # GH#23925 _get_numeric_data may drop all columns
+        df = pd.DataFrame(pd.date_range("1/1/18", periods=5))
+        result = df.quantile(0.5)
+        expected = pd.Series([], index=[], name=0.5)
+        tm.assert_series_equal(result, expected)
+
+        result = df.quantile([0.5])
+        expected = pd.DataFrame([], index=[0.5], columns=[])
+        tm.assert_frame_equal(result, expected)