DEPR: unused 'errors' keyword in where, mask

doc/source/whatsnew/v1.4.0.rst

@@ -397,7 +397,7 @@ Other Deprecations
 - Deprecated silent dropping of columns that raised a ``TypeError``, ``DataError``, and some cases of ``ValueError`` in :meth:`Series.aggregate`, :meth:`DataFrame.aggregate`, :meth:`Series.groupby.aggregate`, and :meth:`DataFrame.groupby.aggregate` when used with a list (:issue:`43740`)
 - Deprecated casting behavior when setting timezone-aware value(s) into a timezone-aware :class:`Series` or :class:`DataFrame` column when the timezones do not match. Previously this cast to object dtype. In a future version, the values being inserted will be converted to the series or column's existing timezone (:issue:`37605`)
 - Deprecated casting behavior when passing an item with mismatched-timezone to :meth:`DatetimeIndex.insert`, :meth:`DatetimeIndex.putmask`, :meth:`DatetimeIndex.where` :meth:`DatetimeIndex.fillna`, :meth:`Series.mask`, :meth:`Series.where`, :meth:`Series.fillna`, :meth:`Series.shift`, :meth:`Series.replace`, :meth:`Series.reindex` (and :class:`DataFrame` column analogues). In the past this has cast to object dtype. In a future version, these will cast the passed item to the index or series's timezone (:issue:`37605`)
--
+- Deprecated the 'where' keyword argument in :meth:`Series.where`, :meth:`DataFrame.where`, :meth:`Series.mask`, and meth:`DataFrame.mask`; in a future version the argument will be removed (:issue:`44294`)
 
 .. ---------------------------------------------------------------------------
 

pandas/core/frame.py

@@ -10907,7 +10907,7 @@ def where(
         inplace=False,
         axis=None,
         level=None,
-        errors="raise",
+        errors=lib.no_default,
         try_cast=lib.no_default,
     ):
         return super().where(cond, other, inplace, axis, level, errors, try_cast)
@@ -10922,7 +10922,7 @@ def mask(
         inplace=False,
         axis=None,
         level=None,
-        errors="raise",
+        errors=lib.no_default,
         try_cast=lib.no_default,
     ):
         return super().mask(cond, other, inplace, axis, level, errors, try_cast)

pandas/core/generic.py

@@ -8900,14 +8900,24 @@ def _where(
         inplace=False,
         axis=None,
         level=None,
-        errors="raise",
+        errors=lib.no_default,
     ):
         """
         Equivalent to public method `where`, except that `other` is not
         applied as a function even if callable. Used in __setitem__.
         """
         inplace = validate_bool_kwarg(inplace, "inplace")
 
+        if errors is not lib.no_default:
+            warnings.warn(
+                f"The 'errors' keyword in {type(self).__name__}.where and mask is "
+                "deprecated and will be removed in a future version.",
+                FutureWarning,
+                stacklevel=find_stack_level(),
+            )
+        else:
+            errors = "raise"
+
         if axis is not None:
             axis = self._get_axis_number(axis)
 
@@ -9025,7 +9035,6 @@ def _where(
                 other=other,
                 cond=cond,
                 align=align,
-                errors=errors,
             )
             result = self._constructor(new_data)
             return result.__finalize__(self)
@@ -9044,7 +9053,7 @@ def where(
         inplace=False,
         axis=None,
         level=None,
-        errors="raise",
+        errors=lib.no_default,
         try_cast=lib.no_default,
     ):
         """
@@ -9077,6 +9086,9 @@ def where(
             - 'raise' : allow exceptions to be raised.
             - 'ignore' : suppress exceptions. On error return original object.
 
+            .. deprecated:: 1.4.0
+                Previously was silently ignored.
+
         try_cast : bool, default None
             Try to cast the result back to the input type (if possible).
 
@@ -9197,7 +9209,7 @@ def mask(
         inplace=False,
         axis=None,
         level=None,
-        errors="raise",
+        errors=lib.no_default,
         try_cast=lib.no_default,
     ):
 

pandas/core/internals/array_manager.py

@@ -327,7 +327,7 @@ def apply_with_block(self: T, f, align_keys=None, swap_axis=True, **kwargs) -> T
 
         return type(self)(result_arrays, self._axes)
 
-    def where(self: T, other, cond, align: bool, errors: str) -> T:
+    def where(self: T, other, cond, align: bool) -> T:
         if align:
             align_keys = ["other", "cond"]
         else:
@@ -339,7 +339,6 @@ def where(self: T, other, cond, align: bool, errors: str) -> T:
             align_keys=align_keys,
             other=other,
             cond=cond,
-            errors=errors,
         )
 
     # TODO what is this used for?

pandas/core/internals/blocks.py

@@ -1144,17 +1144,14 @@ def shift(self, periods: int, axis: int = 0, fill_value: Any = None) -> list[Blo
 
         return [self.make_block(new_values)]
 
-    def where(self, other, cond, errors="raise") -> list[Block]:
+    def where(self, other, cond) -> list[Block]:
         """
         evaluate the block; return result block(s) from the result
 
         Parameters
         ----------
         other : a ndarray/object
         cond : np.ndarray[bool], SparseArray[bool], or BooleanArray
-        errors : str, {'raise', 'ignore'}, default 'raise'
-            - ``raise`` : allow exceptions to be raised
-            - ``ignore`` : suppress exceptions. On error return original object
 
         Returns
         -------
@@ -1163,7 +1160,6 @@ def where(self, other, cond, errors="raise") -> list[Block]:
         assert cond.ndim == self.ndim
         assert not isinstance(other, (ABCIndex, ABCSeries, ABCDataFrame))
 
-        assert errors in ["raise", "ignore"]
         transpose = self.ndim == 2
 
         values = self.values
@@ -1185,9 +1181,8 @@ def where(self, other, cond, errors="raise") -> list[Block]:
             # or if we are a single block (ndim == 1)
             if not self._can_hold_element(other):
                 # we cannot coerce, return a compat dtype
-                # we are explicitly ignoring errors
                 block = self.coerce_to_target_dtype(other)
-                blocks = block.where(orig_other, cond, errors=errors)
+                blocks = block.where(orig_other, cond)
                 return self._maybe_downcast(blocks, "infer")
 
             # error: Argument 1 to "setitem_datetimelike_compat" has incompatible type
@@ -1586,7 +1581,7 @@ def shift(self, periods: int, axis: int = 0, fill_value: Any = None) -> list[Blo
         new_values = self.values.shift(periods=periods, fill_value=fill_value)
         return [self.make_block_same_class(new_values)]
 
-    def where(self, other, cond, errors="raise") -> list[Block]:
+    def where(self, other, cond) -> list[Block]:
 
         cond = extract_bool_array(cond)
         assert not isinstance(other, (ABCIndex, ABCSeries, ABCDataFrame))
@@ -1619,7 +1614,7 @@ def where(self, other, cond, errors="raise") -> list[Block]:
                     # For now at least only support casting e.g.
                     #  Interval[int64]->Interval[float64]
                     raise
-                return blk.where(other, cond, errors)
+                return blk.where(other, cond)
             raise
 
         return [self.make_block_same_class(result)]
@@ -1704,15 +1699,15 @@ def putmask(self, mask, new) -> list[Block]:
         arr.T.putmask(mask, new)
         return [self]
 
-    def where(self, other, cond, errors="raise") -> list[Block]:
+    def where(self, other, cond) -> list[Block]:
         arr = self.values
 
         cond = extract_bool_array(cond)
 
         try:
             res_values = arr.T._where(cond, other).T
         except (ValueError, TypeError):
-            return Block.where(self, other, cond, errors=errors)
+            return Block.where(self, other, cond)
 
         nb = self.make_block_same_class(res_values)
         return [nb]

pandas/core/internals/managers.py

@@ -315,7 +315,7 @@ def apply(
         out = type(self).from_blocks(result_blocks, self.axes)
         return out
 
-    def where(self: T, other, cond, align: bool, errors: str) -> T:
+    def where(self: T, other, cond, align: bool) -> T:
         if align:
             align_keys = ["other", "cond"]
         else:
@@ -327,7 +327,6 @@ def where(self: T, other, cond, align: bool, errors: str) -> T:
             align_keys=align_keys,
             other=other,
             cond=cond,
-            errors=errors,
         )
 
     def setitem(self: T, indexer, value) -> T:

pandas/core/series.py

@@ -5461,7 +5461,7 @@ def where(
         inplace=False,
         axis=None,
         level=None,
-        errors="raise",
+        errors=lib.no_default,
         try_cast=lib.no_default,
     ):
         return super().where(cond, other, inplace, axis, level, errors, try_cast)
@@ -5476,7 +5476,7 @@ def mask(
         inplace=False,
         axis=None,
         level=None,
-        errors="raise",
+        errors=lib.no_default,
         try_cast=lib.no_default,
     ):
         return super().mask(cond, other, inplace, axis, level, errors, try_cast)

pandas/tests/series/methods/test_fillna.py

@@ -147,15 +147,18 @@ def test_fillna_consistency(self):
         )
         tm.assert_series_equal(result, expected)
 
-        # where (we ignore the errors=)
-        result = ser.where(
-            [True, False], Timestamp("20130101", tz="US/Eastern"), errors="ignore"
-        )
+        msg = "The 'errors' keyword in "
+        with tm.assert_produces_warning(FutureWarning, match=msg):
+            # where (we ignore the errors=)
+            result = ser.where(
+                [True, False], Timestamp("20130101", tz="US/Eastern"), errors="ignore"
+            )
         tm.assert_series_equal(result, expected)
 
-        result = ser.where(
-            [True, False], Timestamp("20130101", tz="US/Eastern"), errors="ignore"
-        )
+        with tm.assert_produces_warning(FutureWarning, match=msg):
+            result = ser.where(
+                [True, False], Timestamp("20130101", tz="US/Eastern"), errors="ignore"
+            )
         tm.assert_series_equal(result, expected)
 
         # with a non-datetime