# What’s new in 1.0.1 (February 5, 2020)¶

These are the changes in pandas 1.0.1. See Release Notes for a full changelog including other versions of pandas.

## Fixed regressions¶

Fixed regression in

`DataFrame`

setting values with a slice (e.g.`df[-4:] = 1`

) indexing by label instead of position (GH31469)Fixed regression when indexing a

`Series`

or`DataFrame`

indexed by`DatetimeIndex`

with a slice containg a`datetime.date`

(GH31501)Fixed regression in

`DataFrame.__setitem__`

raising an`AttributeError`

with a`MultiIndex`

and a non-monotonic indexer (GH31449)Fixed regression in

`Series`

multiplication when multiplying a numeric`Series`

with >10000 elements with a timedelta-like scalar (GH31457)Fixed regression in

`.groupby().agg()`

raising an`AssertionError`

for some reductions like`min`

on object-dtype columns (GH31522)Fixed regression in

`.groupby()`

aggregations with categorical dtype using Cythonized reduction functions (e.g.`first`

) (GH31450)Fixed regression in

`GroupBy.apply()`

if called with a function which returned a non-pandas non-scalar object (e.g. a list or numpy array) (GH31441)Fixed regression in

`DataFrame.groupby()`

whereby taking the minimum or maximum of a column with period dtype would raise a`TypeError`

. (GH31471)Fixed regression in

`DataFrame.groupby()`

with an empty DataFrame grouping by a level of a MultiIndex (GH31670).Fixed regression in

`DataFrame.apply()`

with object dtype and non-reducing function (GH31505)Fixed regression in

`to_datetime()`

when parsing non-nanosecond resolution datetimes (GH31491)Fixed regression in

`to_csv()`

where specifying an`na_rep`

might truncate the values written (GH31447)Fixed regression in

`Categorical`

construction with`numpy.str_`

categories (GH31499)Fixed regression in

`DataFrame.loc()`

and`DataFrame.iloc()`

when selecting a row containing a single`datetime64`

or`timedelta64`

column (GH31649)Fixed regression where setting

`pd.options.display.max_colwidth`

was not accepting negative integer. In addition, this behavior has been deprecated in favor of using`None`

(GH31532)Fixed regression in objTOJSON.c fix return-type warning (GH31463)

Fixed regression in

`qcut()`

when passed a nullable integer. (GH31389)Fixed regression in assigning to a

`Series`

using a nullable integer dtype (GH31446)Fixed performance regression when indexing a

`DataFrame`

or`Series`

with a`MultiIndex`

for the index using a list of labels (GH31648)Fixed regression in

`read_csv()`

used in file like object`RawIOBase`

is not recognize`encoding`

option (GH31575)

## Deprecations¶

Support for negative integer for

`pd.options.display.max_colwidth`

is deprecated in favor of using`None`

(GH31532)

## Bug fixes¶

**Datetimelike**

Fixed bug in

`to_datetime()`

raising when`cache=True`

and out-of-bound values are present (GH31491)

**Numeric**

Bug in dtypes being lost in

`DataFrame.__invert__`

(`~`

operator) with mixed dtypes (GH31183) and for extension-array backed`Series`

and`DataFrame`

(GH23087)

**Plotting**

Plotting tz-aware timeseries no longer gives UserWarning (GH31205)

**Interval**

Bug in

`Series.shift()`

with`interval`

dtype raising a`TypeError`

when shifting an interval array of integers or datetimes (GH34195)

## Contributors¶

A total of 7 people contributed patches to this release. People with a “+” by their names contributed a patch for the first time.

Guillaume Lemaitre

Jeff Reback

Joris Van den Bossche

Kaiqi Dong

MeeseeksMachine

Pandas Development Team

Tom Augspurger