Backport PR #35543: REGR: Fix interpolation on empty dataframe (#35764)

Co-authored-by: sanderland <[email protected]>

Author: meeseeksmachine

doc/source/whatsnew/v1.1.1.rst

@@ -19,6 +19,7 @@ Fixed regressions
 - Fixed regression where :func:`read_csv` would raise a ``ValueError`` when ``pandas.options.mode.use_inf_as_na`` was set to ``True`` (:issue:`35493`)
 - Fixed regression where :func:`pandas.testing.assert_series_equal` would raise an error when non-numeric dtypes were passed with ``check_exact=True`` (:issue:`35446`)
 - Fixed regression in :class:`pandas.core.groupby.RollingGroupby` where column selection was ignored (:issue:`35486`)
+- Fixed regression where :meth:`DataFrame.interpolate` would raise a ``TypeError`` when the :class:`DataFrame` was empty (:issue:`35598`).
 - Fixed regression in :meth:`DataFrame.shift` with ``axis=1`` and heterogeneous dtypes (:issue:`35488`)
 - Fixed regression in :meth:`DataFrame.diff` with read-only data (:issue:`35559`)
 - Fixed regression in ``.groupby(..).rolling(..)`` where a segfault would occur with ``center=True`` and an odd number of values (:issue:`35552`)

pandas/core/generic.py

@@ -6799,6 +6799,9 @@ def interpolate(
 
         obj = self.T if should_transpose else self
 
+        if obj.empty:
+            return self
+
         if method not in fillna_methods:
             axis = self._info_axis_number
 

pandas/tests/frame/methods/test_interpolate.py

@@ -34,6 +34,13 @@ def test_interp_basic(self):
         expected.loc[5, "B"] = 9
         tm.assert_frame_equal(result, expected)
 
+    def test_interp_empty(self):
+        # https://github.com/pandas-dev/pandas/issues/35598
+        df = DataFrame()
+        result = df.interpolate()
+        expected = df
+        tm.assert_frame_equal(result, expected)
+
     def test_interp_bad_method(self):
         df = DataFrame(
             {