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# What’s new in 1.1.2 (September 8, 2020)

These are the changes in pandas 1.1.2. See Release notes for a full changelog including other versions of pandas.

## Fixed regressions

- Regression in `DatetimeIndex.intersection()` incorrectly raising `AssertionError` when intersecting against a list (GH 35876)

- Fix regression in updating a column inplace (e.g. using `df['col'].fillna(.., inplace=True)`) (GH 35731)

- Fix regression in `DataFrame.append()` mixing tz-aware and tz-naive datetime columns (GH 35460)

- Performance regression for `RangeIndex.format()` (GH 35712)

- Regression where `MultiIndex.get_loc()` would return a slice spanning the full index when passed an empty list (GH 35878)

- Fix regression in invalid cache after an indexing operation; this can manifest when setting which does not update the data (GH 35521)

- Regression in `DataFrame.replace()` where a `TypeError` would be raised when attempting to replace elements of type `Interval` (GH 35931)

- Fix regression in pickle roundtrip of the `closed` attribute of `IntervalIndex` (GH 35658)

- Fixed regression in `DataFrameGroupBy.agg()` where a `ValueError: buffer source array is read-only` would be raised when the underlying array is read-only (GH 36014)

- Fixed regression in `Series.groupby.rolling()` number of levels of `MultiIndex` in input was compressed to one (GH 36018)

- Fixed regression in `DataFrameGroupBy` on an empty `DataFrame` (GH 36197)

## Bug fixes

- Bug in `DataFrame.eval()` with `object` dtype column binary operations (GH 35794)

- Bug in `Series` constructor raising a `TypeError` when constructing sparse datetime64 dtypes (GH 35762)

- Bug in `DataFrame.apply()` with `result_type="reduce"` returning with incorrect index (GH 35683)

- Bug in `Series.astype()` and `DataFrame.astype()` not respecting the `errors` argument when set to `"ignore"` for extension dtypes (GH 35471)

- Bug in `DateTimeIndex.format()` and `PeriodIndex.format()` with `name=True` setting the first item to `"None"` where it should be `""` (GH 35712)

- Bug in `Float64Index.__contains__()` incorrectly raising `TypeError` instead of returning `False` (GH 35788)

- Bug in `Series` constructor incorrectly raising a `TypeError` when passed an ordered set (GH 36044)

- Bug in `Series.dt.isocalendar()` and `DatetimeIndex.isocalendar()` that returned incorrect year for certain dates (GH 36032)

- Bug in `DataFrame` indexing returning an incorrect `Series` in some cases when the series has been altered and a cache not invalidated (GH 33675)

- Bug in `DataFrame.corr()` causing subsequent indexing lookups to be incorrect (GH 35882)

- Bug in `import_optional_dependency()` returning incorrect package names in cases where package name is different from import name (GH 35948)

- Bug when setting empty `DataFrame` column to a `Series` in preserving name of index in frame (GH 31368)

## Other

- `factorize()` now supports `na_sentinel=None` to include NaN in the uniques of the values and remove `dropna` keyword which was unintentionally exposed to public facing API in 1.1 version from `factorize()` (GH 35667)

- `DataFrame.plot()` and `Series.plot()` raise `UserWarning` about usage of `FixedFormatter` and `FixedLocator` (GH 35684 and GH 35945)

## Contributors

A total of 16 people contributed patches to this release. People with a “+” by their names contributed a patch for the first time.

- Ali McMaster

- Asish Mahapatra

- Daniel Saxton

- Fangchen Li

- Harsh Sharma +

- Irv Lustig

- Jeet Parekh +

- Joris Van den Bossche

- Kaiqi Dong

- Matthew Roeschke

- MeeseeksMachine

- Pandas Development Team

- Simon Hawkins

- Terji Petersen

- jbrockmendel

- patrick