BUG: fix non-existent variable in NDFrame.interpolate

doc/source/whatsnew/v1.0.0.rst

@@ -249,6 +249,7 @@ Bug fixes
 ~~~~~~~~~
 
 - Bug in :meth:`DataFrame.to_html` when using ``formatters=<list>`` and ``max_cols`` together. (:issue:`25955`)
+- Bug in :meth:`DataFrame.interpolate` where specifying axis by name references variable before it is assigned (:issue:`29132`)
 
 Categorical
 ^^^^^^^^^^^

pandas/core/generic.py

@@ -7023,14 +7023,15 @@ def interpolate(
  """
  inplace = validate_bool_kwarg(inplace, "inplace")
 
+ axis = self._get_axis_number(axis)
+
  if axis == 0:
  ax = self._info_axis_name
  _maybe_transposed_self = self
  elif axis == 1:
  _maybe_transposed_self = self.T
  ax = 1
- else:
- _maybe_transposed_self = self
+
  ax = _maybe_transposed_self._get_axis_number(ax)
 
  if _maybe_transposed_self.ndim == 2:

pandas/tests/generic/test_generic.py

@@ -948,3 +948,8 @@ def test_deprecated_get_dtype_counts(self):
  df = DataFrame([1])
  with tm.assert_produces_warning(FutureWarning):
  df.get_dtype_counts()
+
+ @pytest.mark.parametrize("axis", [0, 1, "index", "columns", "rows"])
+ def test_interpolate_axis_argument(self, axis):
+ # GH 29142
+ assert DataFrame([0]).interpolate(axis=axis)