v0.20.0.txt

.. _whatsnew_0200:

v0.20.0 (????, 2016)
--------------------

This is a major release from 0.19 and includes a small number of API changes, several new features,
enhancements, and performance improvements along with a large number of bug fixes. We recommend that all
users upgrade to this version.

Highlights include:


Check the :ref:`API Changes <whatsnew_0200.api_breaking>` and :ref:`deprecations <whatsnew_0200.deprecations>` before updating.

.. contents:: What's new in v0.19.0
    :local:
    :backlinks: none

.. _whatsnew_0200.enhancements:

New features
~~~~~~~~~~~~





.. _whatsnew_0200.enhancements.other:

Other enhancements
^^^^^^^^^^^^^^^^^^

- ``pd.read_excel`` now preserves sheet order when using ``sheetname=None`` (:issue:`9930`)
- Strings passed to ``DataFrame.groupby()`` as the ``by`` parameter may now reference either column names or index level names (:issue:`5677`)

.. ipython:: python

   arrays = [['bar', 'bar', 'baz', 'baz', 'foo', 'foo', 'qux', 'qux'],
             ['one', 'two', 'one', 'two', 'one', 'two', 'one', 'two']]

   index = pd.MultiIndex.from_arrays(arrays, names=['first', 'second'])

   df = pd.DataFrame({'A': [1, 1, 1, 1, 2, 2, 3, 3],
                      'B': np.arange(8)},
                     index=index)

   df.groupby(['second', 'A']).sum()


.. _whatsnew_0200.api_breaking:

Backwards incompatible API changes
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

.. _whatsnew_0200.api:






Other API Changes
^^^^^^^^^^^^^^^^^

.. _whatsnew_0200.deprecations:

Deprecations
^^^^^^^^^^^^





.. _whatsnew_0200.prior_deprecations:

Removal of prior version deprecations/changes
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

- ``pd.to_datetime`` and ``pd.to_timedelta`` have dropped the ``coerce`` parameter in favor of ``errors`` (:issue:`13602`)




.. _whatsnew_0200.performance:

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





.. _whatsnew_0200.bug_fixes:

Bug Fixes
~~~~~~~~~