.. _whatsnew_0900:

v0.9.0 (October 7, 2012)
------------------------

This is a major release from 0.8.1 and includes several new features and
enhancements along with a large number of bug fixes. New features include
vectorized unicode encoding/decoding for `Series.str`, `to_latex` method to
DataFrame, more flexible parsing of boolean values, and enabling the download of
options data from Yahoo! Finance.

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

  - Add ``encode`` and ``decode`` for unicode handling to :ref:`vectorized
    string processing methods <basics.string_methods>` in Series.str  (GH1706_)
  - Add ``DataFrame.to_latex`` method (GH1735_)
  - Add convenient expanding window equivalents of all rolling_* ops (GH1785_)
  - Add Options class to pandas.io.data for fetching options data from Yahoo!
    Finance (GH1748_, GH1739_)
  - More flexible parsing of boolean values (Yes, No, TRUE, FALSE, etc)
    (GH1691_, GH1295_)
  - Add ``level`` parameter to ``Series.reset_index``
  - ``TimeSeries.between_time`` can now select times across midnight (GH1871_)
  - Series constructor can now handle generator as input (GH1679_)
  - ``DataFrame.dropna`` can now take multiple axes (tuple/list) as input
    (GH924_)
  - Enable ``skip_footer`` parameter in ``ExcelFile.parse`` (GH1843_)

API changes
~~~~~~~~~~~

  - The default column names when ``header=None`` and no columns names passed to
    functions like ``read_csv`` has changed to be more Pythonic and amenable to
    attribute access:

.. ipython:: python

   from StringIO import StringIO

   data = '0,0,1\n1,1,0\n0,1,0'
   df = read_csv(StringIO(data), header=None)
   df


- Creating a Series from another Series, passing an index, will cause reindexing
  to happen inside rather than treating the Series like an ndarray. Technically
  improper usages like ``Series(df[col1], index=df[col2])11 that worked before
  "by accident" (this was never intended) will lead to all NA Series in some
  cases. To be perfectly clear:

.. ipython:: python

   s1 = Series([1, 2, 3])
   s1

   s2 = Series(s1, index=['foo', 'bar', 'baz'])
   s2

- Deprecated ``day_of_year`` API removed from PeriodIndex, use ``dayofyear``
  (GH1723_)

- Don't modify NumPy suppress printoption to True at import time

- The internal HDF5 data arrangement for DataFrames has been transposed.  Legacy
  files will still be readable by HDFStore (GH1834_, GH1824_)

- Legacy cruft removed: pandas.stats.misc.quantileTS

- Use ISO8601 format for Period repr: monthly, daily, and on down (GH1776_)

- Empty DataFrame columns are now created as object dtype. This will prevent a
  class of TypeErrors that was occurring in code where the dtype of a column
  would depend on the presence of data or not (e.g. a SQL query having results)
  (GH1783_)

- Setting parts of DataFrame/Panel using ix now aligns input Series/DataFrame
  (GH1630_)

- ``first`` and ``last`` methods in ``GroupBy`` no longer drop non-numeric
  columns (GH1809_)

- Resolved inconsistencies in specifying custom NA values in text parser.
  ``na_values`` of type dict no longer override default NAs unless
  ``keep_default_na`` is set to false explicitly (GH1657_)

- ``DataFrame.dot`` will not do data alignment, and also work with Series
  (GH1915_)


See the `full release notes
<https://github.com/pydata/pandas/blob/master/RELEASE.rst>`__ or issue tracker
on GitHub for a complete list.

.. _GH1706: https://github.com/pydata/pandas/issues/1706
.. _GH1735: https://github.com/pydata/pandas/issues/1735
.. _GH1785: https://github.com/pydata/pandas/issues/1785
.. _GH1748: https://github.com/pydata/pandas/issues/1748
.. _GH1739: https://github.com/pydata/pandas/issues/1739
.. _GH1691: https://github.com/pydata/pandas/issues/1691
.. _GH1295: https://github.com/pydata/pandas/issues/1295
.. _GH1723: https://github.com/pydata/pandas/issues/1723
.. _GH1834: https://github.com/pydata/pandas/issues/1834
.. _GH1824: https://github.com/pydata/pandas/issues/1824
.. _GH1776: https://github.com/pydata/pandas/issues/1776
.. _GH1783: https://github.com/pydata/pandas/issues/1783
.. _GH1630: https://github.com/pydata/pandas/issues/1630
.. _GH1809: https://github.com/pydata/pandas/issues/1809
.. _GH1657: https://github.com/pydata/pandas/issues/1657
.. _GH1871: https://github.com/pydata/pandas/issues/1871
.. _GH1679: https://github.com/pydata/pandas/issues/1679
.. _GH1915: https://github.com/pydata/pandas/issues/1915
.. _GH924: https://github.com/pydata/pandas/issues/924
.. _GH1843: https://github.com/pydata/pandas/issues/1843
