v0.19.1.txt

.. _whatsnew_0191:

v0.19.1 (????, 2016)
---------------------

This is a minor bug-fix release from 0.19.0 and includes a large number of
bug fixes along with several new features, enhancements, and performance improvements.
We recommend that all users upgrade to this version.

Highlights include:


.. contents:: What's new in v0.19.1
    :local:
    :backlinks: none


.. _whatsnew_0191.performance:

Performance Improvements
~~~~~~~~~~~~~~~~~~~~~~~~

- Fixed performance regression in factorization of ``Period`` data (:issue:`14338`)
- Improved Performance in ``.to_json()`` when ``lines=True`` (:issue:`14408`)





.. _whatsnew_0191.bug_fixes:

Bug Fixes
~~~~~~~~~




- Bug in localizing an ambiguous timezone when a boolean is passed (:issue:`14402`)







- ``pd.merge()`` will raise ``ValueError`` with non-boolean parameters in passed boolean type arguments (:issue:`14434`)


- Bug in ``Timestamp`` where dates very near the minimum (1677-09) could underflow on creation (:issue:`14415`)

- Bug in ``pd.concat`` where names of the ``keys`` were not propagated to the resulting ``MultiIndex`` (:issue:`14252`)
- Bug in ``pd.concat`` where ``axis`` cannot take string parameters ``'rows'`` or ``'columns'`` (:issue:`14369`)
- Bug in ``pd.concat`` with dataframes heterogeneous in length and tuple ``keys`` (:issue:`14438`)
- Bug in ``MultiIndex.set_levels`` where illegal level values were still set after raising an error (:issue:`13754`)
- Bug in ``DataFrame.to_json`` where ``lines=True`` and a value contained a ``}`` character (:issue:`14391`)
- Bug in ``df.groupby`` causing an ``AttributeError`` when grouping a single index frame by a column and the index level (:issue`14327`)

- Bug in ``pd.pivot_table`` may raise ``TypeError`` or ``ValueError`` when ``index`` or ``columns``
  is not scalar and ``values`` is not specified (:issue:`14380`)
- corrrecly raise ``ValueError`` on empty input to pd.eval() and df.query() (:issue: `13139`)