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 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)

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)

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