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# What’s new in 1.0.2 (March 12, 2020)

These are the changes in pandas 1.0.2. See Release notes for a full changelog including other versions of pandas.

## Fixed regressions

Groupby

- Fixed regression in `DataFrameGroupBy.agg()` and `SeriesGroupBy.agg()` which were failing on frames with `MultiIndex` columns and a custom function (GH 31777)

- Fixed regression in `groupby(..).rolling(..).apply()` (`RollingGroupby`) where the `raw` parameter was ignored (GH 31754)

- Fixed regression in `rolling(..).corr()` when using a time offset (GH 31789)

- Fixed regression in `groupby(..).nunique()` which was modifying the original values if `NaN` values were present (GH 31950)

- Fixed regression in `DataFrame.groupby` raising a `ValueError` from an internal operation (GH 31802)

- Fixed regression in `DataFrameGroupBy.agg()` and `SeriesGroupBy.agg()` calling a user-provided function an extra time on an empty input (GH 31760)

I/O

- Fixed regression in `read_csv()` in which the `encoding` option was not recognized with certain file-like objects (GH 31819)

- Fixed regression in `DataFrame.to_excel()` when the `columns` keyword argument is passed (GH 31677)

- Fixed regression in `ExcelFile` where the stream passed into the function was closed by the destructor. (GH 31467)

- Fixed regression where `read_pickle()` raised a `UnicodeDecodeError` when reading a py27 pickle with `MultiIndex` column (GH 31988).

Reindexing/alignment

- Fixed regression in `Series.align()` when `other` is a `DataFrame` and `method` is not `None` (GH 31785)

- Fixed regression in `DataFrame.reindex()` and `Series.reindex()` when reindexing with (tz-aware) index and `method=nearest` (GH 26683)

- Fixed regression in `DataFrame.reindex_like()` on a `DataFrame` subclass raised an `AssertionError` (GH 31925)

- Fixed regression in `DataFrame` arithmetic operations with mis-matched columns (GH 31623)

Other

- Fixed regression in joining on `DatetimeIndex` or `TimedeltaIndex` to preserve `freq` in simple cases (GH 32166)

- Fixed regression in `Series.shift()` with `datetime64` dtype when passing an integer `fill_value` (GH 32591)

- Fixed regression in the repr of an object-dtype `Index` with bools and missing values (GH 32146)

## Indexing with nullable boolean arrays

Previously indexing with a nullable Boolean array containing `NA` would raise a `ValueError`, however this is now permitted with `NA` being treated as `False`. (GH 31503)

    In [1]: s = pd.Series([1, 2, 3, 4])

    In [2]: mask = pd.array([True, True, False, None], dtype="boolean")

    In [3]: s
    Out[3]:
    0    1
    1    2
    2    3
    3    4
    Length: 4, dtype: int64

    In [4]: mask
    Out[4]:
    <BooleanArray>
    [True, True, False, <NA>]
    Length: 4, dtype: boolean

pandas 1.0.0-1.0.1

    >>> s[mask]
    Traceback (most recent call last):
    ...
    ValueError: cannot mask with array containing NA / NaN values

pandas 1.0.2

    In [5]: s[mask]
    Out[5]:
    0    1
    1    2
    Length: 2, dtype: int64

## Bug fixes

Datetimelike

- Bug in `Series.astype()` not copying for tz-naive and tz-aware `datetime64` dtype (GH 32490)

- Bug where `to_datetime()` would raise when passed `pd.NA` (GH 32213)

- Improved error message when subtracting two `Timestamp` that result in an out-of-bounds `Timedelta` (GH 31774)

Categorical

- Fixed bug where `Categorical.from_codes()` improperly raised a `ValueError` when passed nullable integer codes. (GH 31779)

- Fixed bug where `Categorical()` constructor would raise a `TypeError` when given a numpy array containing `pd.NA`. (GH 31927)

- Bug in `Categorical` that would ignore or crash when calling `Series.replace()` with a list-like `to_replace` (GH 31720)

I/O

- Using `pd.NA` with `DataFrame.to_json()` now correctly outputs a null value instead of an empty object (GH 31615)

- Bug in `pandas.json_normalize()` when value in meta path is not iterable (GH 31507)

- Fixed pickling of `pandas.NA`. Previously a new object was returned, which broke computations relying on `NA` being a singleton (GH 31847)

- Fixed bug in parquet roundtrip with nullable unsigned integer dtypes (GH 31896).

Experimental dtypes

- Fixed bug in `DataFrame.convert_dtypes()` for columns that were already using the `"string"` dtype (GH 31731).

- Fixed bug in `DataFrame.convert_dtypes()` for series with mix of integers and strings (GH 32117)

- Fixed bug in `DataFrame.convert_dtypes()` where `BooleanDtype` columns were converted to `Int64` (GH 32287)

- Fixed bug in setting values using a slice indexer with string dtype (GH 31772)

- Fixed bug where `DataFrameGroupBy.first()`, `SeriesGroupBy.first()`, `DataFrameGroupBy.last()`, and `SeriesGroupBy.last()` would raise a `TypeError` when groups contained `pd.NA` in a column of object dtype (GH 32123)

- Fixed bug where `DataFrameGroupBy.mean()`, `DataFrameGroupBy.median()`, `DataFrameGroupBy.var()`, and `DataFrameGroupBy.std()` would raise a `TypeError` on `Int64` dtype columns (GH 32219)

Strings

- Using `pd.NA` with `Series.str.repeat()` now correctly outputs a null value instead of raising error for vector inputs (GH 31632)

Rolling

- Fixed rolling operations with variable window (defined by time duration) on decreasing time index (GH 32385).

## Contributors

A total of 25 people contributed patches to this release. People with a “+” by their names contributed a patch for the first time.

- Anna Daglis +

- Daniel Saxton

- Irv Lustig

- Jan Škoda

- Joris Van den Bossche

- Justin Zheng

- Kaiqi Dong

- Kendall Masse

- Marco Gorelli

- Matthew Roeschke

- MeeseeksMachine

- MomIsBestFriend

- Pandas Development Team

- Pedro Reys +

- Prakhar Pandey

- Robert de Vries +

- Rushabh Vasani

- Simon Hawkins

- Stijn Van Hoey

- Terji Petersen

- Tom Augspurger

- William Ayd

- alimcmaster1

- gfyoung

- jbrockmendel