Cleanup

Author: rhshadrach

doc/source/whatsnew/v3.0.0.rst

@@ -390,9 +390,9 @@ and users can skip the check by explicitly specifying ``sort=True`` or
 ``sort=False``.
 
 This deprecation can also impact pandas' internal usage of :func:`concat`.
-While we have investigated uses of :func:`concat` to determine if this could lead
-to a change in behavior of other functions and methods in the API, it is
-possible some have been missed. In order to be cautious here, pandas has *not*
+Here cases where :func:`concat` was sorting a :class:`DatetimeIndex` but not
+other indexes are considered bugs and have been fixed as noted below. However
+it is possible some have been missed. In order to be cautious here, pandas has *not*
 added ``sort=False`` to any internal calls where we believe behavior should not change.
 If we have missed something, users will not experience a behavior change but they
 will receive a warning about :func:`concat` even though they are not directly
@@ -429,6 +429,14 @@ we may address any potential behavior changes.
 
     pd.concat([df1, df2], axis=1, sort=False)
 
+Cases where pandas' internal usage of :func:`concat` resulted in inconsistent sorting
+that are now fixed in this release are as follows.
+
+- :meth:`Series.apply` and :meth:`DataFrame.apply` with a list-like or dict-like ``func`` argument.
+- :meth:`Series.shift`, :meth:`DataFrame.shift`, :meth:`.SeriesGroupBy.shift`, :meth:`.DataFrameGroupBy.shift` with the ``periods`` argument a list of length greater than 1.
+- :meth:`DataFrame.join` with ``other`` a list of one or more Series or DataFrames and ``how="inner"``, ``how="left"``, or ``how="right"``.
+- :meth:`Series.str.cat` with ``others`` a Series or DataFrame.
+
 .. _whatsnew_300.api_breaking.value_counts_sorting:
 
 Changed behavior in :meth:`DataFrame.value_counts` and :meth:`DataFrameGroupBy.value_counts` when ``sort=False``
@@ -1233,7 +1241,6 @@ Groupby/resample/rolling
 - Bug in :meth:`DataFrameGroupBy.apply` with ``as_index=False`` that was returning :class:`MultiIndex` instead of returning :class:`Index`. (:issue:`58291`)
 - Bug in :meth:`DataFrameGroupBy.cumsum` and :meth:`DataFrameGroupBy.cumprod` where ``numeric_only`` parameter was passed indirectly through kwargs instead of passing directly. (:issue:`58811`)
 - Bug in :meth:`DataFrameGroupBy.cumsum` where it did not return the correct dtype when the label contained ``None``. (:issue:`58811`)
-- Bug in :meth:`DataFrameGroupBy.shift` where the resulting index would be sorted if the input is a :class:`DatetimeIndex` and multiple periods are specified (:issue:`62843`)
 - Bug in :meth:`DataFrameGroupby.transform` and :meth:`SeriesGroupby.transform` with a reducer and ``observed=False`` that coerces dtype to float when there are unobserved categories. (:issue:`55326`)
 - Bug in :meth:`Rolling.apply` for ``method="table"`` where column order was not being respected due to the columns getting sorted by default. (:issue:`59666`)
 - Bug in :meth:`Rolling.apply` where the applied function could be called on fewer than ``min_period`` periods if ``method="table"``. (:issue:`58868`)

pandas/core/apply.py

@@ -382,7 +382,7 @@ def transform_dict_like(self, func) -> DataFrame:
         for name, how in func.items():
             colg = obj._gotitem(name, ndim=1)
             results[name] = colg.transform(how, 0, *args, **kwargs)
-        return concat(results, axis=1)  # nobug
+        return concat(results, axis=1)
 
     def transform_str_or_callable(self, func) -> DataFrame | Series:
         """
@@ -485,7 +485,7 @@ def wrap_results_list_like(
         obj = self.obj
 
         try:
-            return concat(results, keys=keys, axis=1, sort=False)  # nobug
+            return concat(results, keys=keys, axis=1, sort=False)
         except TypeError as err:
             # we are concatting non-NDFrame objects,
             # e.g. a list of scalars
@@ -635,7 +635,7 @@ def wrap_results_dict_like(
                 keys_to_use = ktu
 
             axis: AxisInt = 0 if isinstance(obj, ABCSeries) else 1
-            result = concat(  # nobug
+            result = concat(
                 results,
                 axis=axis,
                 keys=keys_to_use,

pandas/core/arrays/arrow/accessors.py

@@ -496,6 +496,6 @@ def explode(self) -> DataFrame:
         from pandas import concat
 
         pa_type = self._pa_array.type
-        return concat(  # nobug
+        return concat(
             [self.field(i) for i in range(pa_type.num_fields)], axis="columns"
         )

pandas/core/arrays/categorical.py

@@ -2690,7 +2690,7 @@ def describe(self) -> DataFrame:
         from pandas import Index
         from pandas.core.reshape.concat import concat
 
-        result = concat([counts, freqs], ignore_index=True, axis=1)  # nobug
+        result = concat([counts, freqs], ignore_index=True, axis=1)
         result.columns = Index(["counts", "freqs"])
         result.index.name = "categories"
 

pandas/core/frame.py

@@ -6130,7 +6130,7 @@ def shift(
                     .shift(periods=period, freq=freq, axis=axis, fill_value=fill_value)
                     .add_suffix(f"{suffix}_{period}" if suffix else f"_{period}")
                 )
-            return concat(shifted_dataframes, axis=1, sort=False)  # nobug
+            return concat(shifted_dataframes, axis=1, sort=False)
         elif suffix:
             raise ValueError("Cannot specify `suffix` if `periods` is an int.")
         periods = cast(int, periods)
@@ -11166,7 +11166,7 @@ def _append_internal(
 
         from pandas.core.reshape.concat import concat
 
-        result = concat(  # nobug
+        result = concat(
             [self, row_df],
             ignore_index=ignore_index,
         )
@@ -11394,12 +11394,12 @@ def join(
             # join indexes only using concat
             if can_concat:
                 if how == "left":
-                    res = concat(  # nobug
+                    res = concat(
                         frames, axis=1, join="outer", verify_integrity=True, sort=sort
                     )
                     return res.reindex(self.index)
                 else:
-                    return concat(  # nobug
+                    return concat(
                         frames, axis=1, join=how, verify_integrity=True, sort=sort
                     )
 
@@ -11590,7 +11590,7 @@ def _series_round(ser: Series, decimals: int) -> Series:
             return self._constructor(
                 concat(new_cols, axis=1),
                 index=self.index,
-                columns=self.columns,  # nobug
+                columns=self.columns,
             ).__finalize__(self, method="round")
         else:
             return self.copy(deep=False)
@@ -14173,7 +14173,7 @@ def isin(self, values: Series | DataFrame | Sequence | Mapping) -> DataFrame:
             from pandas.core.reshape.concat import concat
 
             values = collections.defaultdict(list, values)
-            result = concat(  # nobug
+            result = concat(
                 (
                     self.iloc[:, [i]].isin(values[col])
                     for i, col in enumerate(self.columns)

pandas/core/generic.py

@@ -6525,7 +6525,7 @@ def astype(
             return self.copy(deep=False)
 
         # GH 19920: retain column metadata after concat
-        result = concat(results, axis=1)  # nobug
+        result = concat(results, axis=1)
         # GH#40810 retain subclass
         # error: Incompatible types in assignment
         # (expression has type "Self", variable has type "DataFrame")
@@ -9507,7 +9507,7 @@ def compare(
 
         # error: List item 0 has incompatible type "NDFrame"; expected
         #  "Union[Series, DataFrame]"
-        diff = concat(  # nobug - self and other must have same index/coluns
+        diff = concat(
             [self, other],  # type: ignore[list-item]
             axis=axis,
             keys=result_names,

pandas/core/groupby/generic.py

@@ -549,7 +549,7 @@ def _aggregate_multiple_funcs(self, arg, *args, **kwargs) -> DataFrame:
         if any(isinstance(x, DataFrame) for x in results.values()):
             from pandas import concat
 
-            res_df = concat(  # nobug
+            res_df = concat(
                 results.values(), axis=1, keys=[key.label for key in results]
             )
             return res_df
@@ -722,7 +722,7 @@ def _transform_general(
         if results:
             from pandas.core.reshape.concat import concat
 
-            concatenated = concat(results, ignore_index=True)  # nobug
+            concatenated = concat(results, ignore_index=True)
             result = self._set_result_index_ordered(concatenated)
         else:
             result = self.obj._constructor(dtype=np.float64)
@@ -2238,7 +2238,7 @@ def _transform_general(self, func, engine, engine_kwargs, *args, **kwargs):
             applied.append(res)
 
         concat_index = obj.columns
-        concatenated = concat(  # nobug
+        concatenated = concat(
             applied, axis=0, verify_integrity=False, ignore_index=True
         )
         concatenated = concatenated.reindex(concat_index, axis=1)
@@ -2530,7 +2530,7 @@ def _apply_to_column_groupbys(self, func) -> DataFrame:
             # concat would raise
             res_df = DataFrame([], columns=columns, index=self._grouper.result_index)
         else:
-            res_df = concat(results, keys=columns, axis=1)  # nobug
+            res_df = concat(results, keys=columns, axis=1)
 
         if not self.as_index:
             res_df.index = default_index(len(res_df))
@@ -3390,9 +3390,7 @@ def _wrap_transform_general_frame(
         # other dimension; this will preserve dtypes
         # GH14457
         if res.index.is_(obj.index):
-            res_frame = concat(
-                [res] * len(group.columns), axis=1, ignore_index=True
-            )  # nobug
+            res_frame = concat([res] * len(group.columns), axis=1, ignore_index=True)
             res_frame.columns = group.columns
             res_frame.index = group.index
         else:

pandas/core/groupby/groupby.py

@@ -5238,7 +5238,7 @@ def shift(
         return (
             shifted_dataframes[0]
             if len(shifted_dataframes) == 1
-            else concat(shifted_dataframes, axis=1, sort=False)  # nobug
+            else concat(shifted_dataframes, axis=1, sort=False)
         )
 
     @final

pandas/core/indexes/base.py

@@ -5379,9 +5379,9 @@ def append(self, other: Index | Sequence[Index]) -> Index:
         names = {obj.name for obj in to_concat}
         name = None if len(names) > 1 else self.name
 
-        return self._concat(to_concat, name)  # nobug
+        return self._concat(to_concat, name)
 
-    def _concat(self, to_concat: list[Index], name: Hashable) -> Index:  # nobug
+    def _concat(self, to_concat: list[Index], name: Hashable) -> Index:
         """
         Concatenate multiple Index objects.
         """

pandas/core/indexes/range.py

@@ -1181,7 +1181,7 @@ def insert(self, loc: int, item) -> Index:
 
         return super().insert(loc, item)
 
-    def _concat(self, indexes: list[Index], name: Hashable) -> Index:  # nobug
+    def _concat(self, indexes: list[Index], name: Hashable) -> Index:
         """
         Overriding parent method for the case of all RangeIndex instances.
 
@@ -1191,7 +1191,7 @@ def _concat(self, indexes: list[Index], name: Hashable) -> Index:  # nobug
         indexes = [RangeIndex(3), RangeIndex(4, 6)] -> Index([0,1,2,4,5], dtype='int64')
         """
         if not all(isinstance(x, RangeIndex) for x in indexes):
-            result = super()._concat(indexes, name)  # nobug
+            result = super()._concat(indexes, name)
             if result.dtype.kind == "i":
                 return self._shallow_copy(result._values)
             return result