CLN: unused args in pad_or_backfill (pandas-dev#53872)

* CLN: unused args in pad_or_backfill

* restore limit_direction validation

Author: jbrockmendel

pandas/core/arrays/datetimelike.py

@@ -2239,7 +2239,6 @@ def interpolate(
         limit,
         limit_direction,
         limit_area,
-        fill_value,
         inplace: bool,
         **kwargs,
     ) -> Self:
@@ -2263,7 +2262,6 @@ def interpolate(
             limit=limit,
             limit_direction=limit_direction,
             limit_area=limit_area,
-            fill_value=fill_value,
             **kwargs,
         )
         if inplace:

pandas/core/arrays/numpy_.py

@@ -267,7 +267,6 @@ def interpolate(
         limit,
         limit_direction,
         limit_area,
-        fill_value,
         inplace: bool,
         **kwargs,
     ) -> Self:
@@ -289,7 +288,6 @@ def interpolate(
             limit=limit,
             limit_direction=limit_direction,
             limit_area=limit_area,
-            fill_value=fill_value,
             **kwargs,
         )
         if inplace:

pandas/core/generic.py

@@ -6891,7 +6891,7 @@ def _deprecate_downcast(self, downcast) -> None:
             )
 
     @final
-    def _fillna_with_method(
+    def _pad_or_backfill(
         self,
         method: Literal["ffill", "bfill", "pad", "backfill"],
         *,
@@ -6908,7 +6908,7 @@ def _fillna_with_method(
         if not self._mgr.is_single_block and axis == 1:
             if inplace:
                 raise NotImplementedError()
-            result = self.T._fillna_with_method(method=method, limit=limit).T
+            result = self.T._pad_or_backfill(method=method, limit=limit).T
 
             return result
 
@@ -7105,8 +7105,8 @@ def fillna(
         axis = self._get_axis_number(axis)
 
         if value is None:
-            return self._fillna_with_method(
-                # error: Argument 1 to "_fillna_with_method" of "NDFrame" has
+            return self._pad_or_backfill(
+                # error: Argument 1 to "_pad_or_backfill" of "NDFrame" has
                 # incompatible type "Optional[Literal['backfill', 'bfill', 'ffill',
                 # 'pad']]"; expected "Literal['ffill', 'bfill', 'pad', 'backfill']"
                 method,  # type: ignore[arg-type]
@@ -7311,7 +7311,7 @@ def ffill(
         """
         self._deprecate_downcast(downcast)
 
-        return self._fillna_with_method(
+        return self._pad_or_backfill(
             "ffill", axis=axis, inplace=inplace, limit=limit, downcast=downcast
         )
 
@@ -7443,7 +7443,7 @@ def bfill(
         3   4.0    7
         """
         self._deprecate_downcast(downcast)
-        return self._fillna_with_method(
+        return self._pad_or_backfill(
             "bfill", axis=axis, inplace=inplace, limit=limit, downcast=downcast
         )
 
@@ -8003,22 +8003,27 @@ def interpolate(
                 "column to a numeric dtype."
             )
 
-        index = missing.get_interp_index(method, obj.index)
+        if "fill_value" in kwargs:
+            raise ValueError(
+                "'fill_value' is not a valid keyword for "
+                f"{type(self).__name__}.interpolate"
+            )
 
         if method.lower() in fillna_methods:
             # TODO(3.0): remove this case
+            # TODO: warn/raise on limit_direction or kwargs which are ignored?
+            #  as of 2023-06-26 no tests get here with either
+
             new_data = obj._mgr.pad_or_backfill(
                 method=method,
                 axis=axis,
-                index=index,
                 limit=limit,
-                limit_direction=limit_direction,
                 limit_area=limit_area,
                 inplace=inplace,
                 downcast=downcast,
-                **kwargs,
             )
         else:
+            index = missing.get_interp_index(method, obj.index)
             axis = self._info_axis_number
             new_data = obj._mgr.interpolate(
                 method=method,
@@ -9980,8 +9985,8 @@ def _align_frame(
         )
 
         if method is not None:
-            left = left._fillna_with_method(method, axis=fill_axis, limit=limit)
-            right = right._fillna_with_method(method, axis=fill_axis, limit=limit)
+            left = left._pad_or_backfill(method, axis=fill_axis, limit=limit)
+            right = right._pad_or_backfill(method, axis=fill_axis, limit=limit)
 
         return left, right, join_index
 
@@ -10057,8 +10062,8 @@ def _align_series(
         if fill_na:
             fill_value, method = validate_fillna_kwargs(fill_value, method)
             if method is not None:
-                left = left._fillna_with_method(method, limit=limit, axis=fill_axis)
-                right = right._fillna_with_method(method, limit=limit)
+                left = left._pad_or_backfill(method, limit=limit, axis=fill_axis)
+                right = right._pad_or_backfill(method, limit=limit)
             else:
                 left = left.fillna(fill_value, limit=limit, axis=fill_axis)
                 right = right.fillna(fill_value, limit=limit)
@@ -11474,7 +11479,7 @@ def pct_change(
         if fill_method is None:
             data = self
         else:
-            data = self._fillna_with_method(fill_method, axis=axis, limit=limit)
+            data = self._pad_or_backfill(fill_method, axis=axis, limit=limit)
 
         shifted = data.shift(periods=periods, freq=freq, axis=axis, **kwargs)
         # Unsupported left operand type for / ("Self")

pandas/core/internals/blocks.py

@@ -1348,25 +1348,19 @@ def pad_or_backfill(
         *,
         method: FillnaOptions = "pad",
         axis: AxisInt = 0,
-        index: Index | None = None,
         inplace: bool = False,
         limit: int | None = None,
-        limit_direction: Literal["forward", "backward", "both"] = "forward",
         limit_area: Literal["inside", "outside"] | None = None,
-        fill_value: Any | None = None,
         downcast: Literal["infer"] | None = None,
         using_cow: bool = False,
         **kwargs,
     ) -> list[Block]:
         return self.interpolate(
             method=method,
             axis=axis,
-            index=index,
             inplace=inplace,
             limit=limit,
-            limit_direction=limit_direction,
             limit_area=limit_area,
-            fill_value=fill_value,
             downcast=downcast,
             using_cow=using_cow,
             **kwargs,
@@ -1382,7 +1376,6 @@ def interpolate(
         limit: int | None = None,
         limit_direction: Literal["forward", "backward", "both"] = "forward",
         limit_area: Literal["inside", "outside"] | None = None,
-        fill_value: Any | None = None,
         downcast: Literal["infer"] | None = None,
         using_cow: bool = False,
         **kwargs,
@@ -1424,7 +1417,6 @@ def interpolate(
                 limit=limit,
                 limit_direction=limit_direction,
                 limit_area=limit_area,
-                fill_value=fill_value,
                 downcast=downcast,
                 **kwargs,
             )
@@ -1440,10 +1432,6 @@ def interpolate(
         # Dispatch to the PandasArray method.
         # We know self.array_values is a PandasArray bc EABlock overrides
         if m is not None:
-            if fill_value is not None:
-                # similar to validate_fillna_kwargs
-                raise ValueError("Cannot pass both fill_value and method")
-
             # TODO: warn about ignored kwargs, limit_direction, index...?
             new_values = cast(PandasArray, self.array_values).pad_or_backfill(
                 method=method,
@@ -1461,7 +1449,6 @@ def interpolate(
                 limit=limit,
                 limit_direction=limit_direction,
                 limit_area=limit_area,
-                fill_value=fill_value,
                 inplace=arr_inplace,
                 **kwargs,
             )

pandas/tests/series/methods/test_interpolate.py

@@ -361,7 +361,7 @@ def test_interp_invalid_method_and_value(self):
         # GH#36624
         ser = Series([1, 3, np.nan, 12, np.nan, 25])
 
-        msg = "Cannot pass both fill_value and method"
+        msg = "'fill_value' is not a valid keyword for Series.interpolate"
         msg2 = "Series.interpolate with method=pad"
         with pytest.raises(ValueError, match=msg):
             with tm.assert_produces_warning(FutureWarning, match=msg2):