TST: deprecation warnings
https://travis-ci.org/pandas-dev/pandas/jobs/381128602

some deprecated usages in tests (can be fixed with multiple PRs)

```
pandas/tests/test_panel.py::TestPanel::()::test_median
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/numpy/lib/function_base.py:4033: RuntimeWarning: All-NaN slice encountered
    r = func(a, **kwargs)
pandas/tests/test_resample.py::TestResamplerGrouper::()::test_tab_complete_ipython6_warning
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/IPython/core/interactiveshell.py:763: UserWarning: Attempting to work in a virtualenv. If you encounter problems, please install IPython inside the virtualenv.
    warn("Attempting to work in a virtualenv. If you encounter problems, please "
pandas/tests/test_window.py::TestMoments::()::test_cmov_window_special[slepian]
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/scipy/signal/windows/windows.py:1541: DeprecationWarning: slepian is deprecated and will be removed in a future version, use dpss instead
    'version, use dpss instead', DeprecationWarning)
pandas/tests/test_window.py::TestMoments::()::test_cmov_window_special_linear_range[slepian]
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/scipy/signal/windows/windows.py:1541: DeprecationWarning: slepian is deprecated and will be removed in a future version, use dpss instead
    'version, use dpss instead', DeprecationWarning)
pandas/tests/categorical/test_warnings.py::TestCategoricalWarnings::()::test_tab_complete_warning
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/IPython/core/interactiveshell.py:763: UserWarning: Attempting to work in a virtualenv. If you encounter problems, please install IPython inside the virtualenv.
    warn("Attempting to work in a virtualenv. If you encounter problems, please "
pandas/tests/frame/test_indexing.py::TestDataFrameIndexing::()::test_getitem_setitem_ix_negative_integers
  /home/travis/build/pandas-dev/pandas/pandas/tests/frame/test_indexing.py:401: DeprecationWarning: 
  .ix is deprecated. Please use
  .loc for label based indexing or
  .iloc for positional indexing
  
  See the documentation here:
  http://pandas.pydata.org/pandas-docs/stable/indexing.html#ix-indexer-is-deprecated
    df.ix[[-1]]
  /home/travis/build/pandas-dev/pandas/pandas/tests/frame/test_indexing.py:404: DeprecationWarning: 
  .ix is deprecated. Please use
  .loc for label based indexing or
  .iloc for positional indexing
  
  See the documentation here:
  http://pandas.pydata.org/pandas-docs/stable/indexing.html#ix-indexer-is-deprecated
    df.ix[:, [-1]]
  /home/travis/build/pandas-dev/pandas/pandas/core/indexing.py:890: DeprecationWarning: 
  .ix is deprecated. Please use
  .loc for label based indexing or
  .iloc for positional indexing
  
  See the documentation here:
  http://pandas.pydata.org/pandas-docs/stable/indexing.html#ix-indexer-is-deprecated
    retval = getattr(retval, self.name)._getitem_axis(key, axis=i)
pandas/tests/frame/test_analytics.py::TestDataFrameAnalytics::()::test_median
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/numpy/lib/function_base.py:4033: RuntimeWarning: All-NaN slice encountered
    r = func(a, **kwargs)
pandas/tests/frame/test_analytics.py::TestDataFrameAnalytics::()::test_median_corner
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/numpy/lib/function_base.py:4033: RuntimeWarning: All-NaN slice encountered
    r = func(a, **kwargs)
pandas/tests/frame/test_missing.py::TestDataFrameMissingData::()::test_fillna_categorical_nan
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/numpy/lib/function_base.py:4033: RuntimeWarning: All-NaN slice encountered
    r = func(a, **kwargs)
pandas/tests/frame/test_api.py::TestDataFrameMisc::()::test_tab_complete_warning
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/IPython/core/interactiveshell.py:763: UserWarning: Attempting to work in a virtualenv. If you encounter problems, please install IPython inside the virtualenv.
    warn("Attempting to work in a virtualenv. If you encounter problems, please "
pandas/tests/groupby/test_filters.py::test_filter_and_transform_with_non_unique_float_index
  /home/travis/build/pandas-dev/pandas/pandas/core/indexes/base.py:3063: FutureWarning: elementwise comparison failed; returning scalar instead, but in the future will perform elementwise comparison
    return self._engine.get_loc(key)
pandas/tests/groupby/test_groupby.py::test_cython_grouper_series_bug_noncontig
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/numpy/lib/nanfunctions.py:1018: RuntimeWarning: Mean of empty slice
    return np.nanmean(a, axis, out=out, keepdims=keepdims)
pandas/tests/groupby/aggregate/test_cython.py::test_cythonized_aggers[median]
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/numpy/lib/nanfunctions.py:1018: RuntimeWarning: Mean of empty slice
    return np.nanmean(a, axis, out=out, keepdims=keepdims)
pandas/tests/indexes/datetimes/test_tools.py::TestGuessDatetimeFormat::()::test_guess_datetime_format_for_array
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/dateutil/parser/__init__.py:46: DeprecationWarning: _timelex is a private class and may break without warning, it will be moved and or renamed in future versions.
    warnings.warn(msg, DeprecationWarning)
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/dateutil/parser/__init__.py:46: DeprecationWarning: _timelex is a private class and may break without warning, it will be moved and or renamed in future versions.
    warnings.warn(msg, DeprecationWarning)
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/dateutil/parser/__init__.py:46: DeprecationWarning: _timelex is a private class and may break without warning, it will be moved and or renamed in future versions.
    warnings.warn(msg, DeprecationWarning)
pandas/tests/indexes/datetimes/test_tools.py::TestToDatetimeInferFormat::()::test_to_datetime_infer_datetime_format_consistent_format[True]
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/dateutil/parser/__init__.py:46: DeprecationWarning: _timelex is a private class and may break without warning, it will be moved and or renamed in future versions.
    warnings.warn(msg, DeprecationWarning)
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/dateutil/parser/__init__.py:46: DeprecationWarning: _timelex is a private class and may break without warning, it will be moved and or renamed in future versions.
    warnings.warn(msg, DeprecationWarning)
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/dateutil/parser/__init__.py:46: DeprecationWarning: _timelex is a private class and may break without warning, it will be moved and or renamed in future versions.
    warnings.warn(msg, DeprecationWarning)
pandas/tests/indexes/datetimes/test_tools.py::TestToDatetimeInferFormat::()::test_to_datetime_infer_datetime_format_consistent_format[False]
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/dateutil/parser/__init__.py:46: DeprecationWarning: _timelex is a private class and may break without warning, it will be moved and or renamed in future versions.
    warnings.warn(msg, DeprecationWarning)
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/dateutil/parser/__init__.py:46: DeprecationWarning: _timelex is a private class and may break without warning, it will be moved and or renamed in future versions.
    warnings.warn(msg, DeprecationWarning)
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/dateutil/parser/__init__.py:46: DeprecationWarning: _timelex is a private class and may break without warning, it will be moved and or renamed in future versions.
    warnings.warn(msg, DeprecationWarning)
pandas/tests/indexes/datetimes/test_tools.py::TestToDatetimeInferFormat::()::test_to_datetime_infer_datetime_format_inconsistent_format[True]
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/dateutil/parser/__init__.py:46: DeprecationWarning: _timelex is a private class and may break without warning, it will be moved and or renamed in future versions.
    warnings.warn(msg, DeprecationWarning)
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/dateutil/parser/__init__.py:46: DeprecationWarning: _timelex is a private class and may break without warning, it will be moved and or renamed in future versions.
    warnings.warn(msg, DeprecationWarning)
pandas/tests/indexes/datetimes/test_tools.py::TestToDatetimeInferFormat::()::test_to_datetime_infer_datetime_format_inconsistent_format[False]
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/dateutil/parser/__init__.py:46: DeprecationWarning: _timelex is a private class and may break without warning, it will be moved and or renamed in future versions.
    warnings.warn(msg, DeprecationWarning)
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/dateutil/parser/__init__.py:46: DeprecationWarning: _timelex is a private class and may break without warning, it will be moved and or renamed in future versions.
    warnings.warn(msg, DeprecationWarning)
pandas/tests/indexes/datetimes/test_tools.py::TestToDatetimeInferFormat::()::test_to_datetime_infer_datetime_format_series_with_nans[True]
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/dateutil/parser/__init__.py:46: DeprecationWarning: _timelex is a private class and may break without warning, it will be moved and or renamed in future versions.
    warnings.warn(msg, DeprecationWarning)
pandas/tests/indexes/datetimes/test_tools.py::TestToDatetimeInferFormat::()::test_to_datetime_infer_datetime_format_series_with_nans[False]
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/dateutil/parser/__init__.py:46: DeprecationWarning: _timelex is a private class and may break without warning, it will be moved and or renamed in future versions.
    warnings.warn(msg, DeprecationWarning)
pandas/tests/indexing/test_indexing.py::TestFancy::()::test_dups_fancy_indexing
  /home/travis/build/pandas-dev/pandas/pandas/tests/indexing/test_indexing.py:200: DeprecationWarning: 
  .ix is deprecated. Please use
  .loc for label based indexing or
  .iloc for positional indexing
  
  See the documentation here:
  http://pandas.pydata.org/pandas-docs/stable/indexing.html#ix-indexer-is-deprecated
    dfnu.ix[['E']]
pandas/tests/io/formats/test_printing.py::TestTableSchemaRepr::()::test_publishes
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/IPython/core/interactiveshell.py:763: UserWarning: Attempting to work in a virtualenv. If you encounter problems, please install IPython inside the virtualenv.
    warn("Attempting to work in a virtualenv. If you encounter problems, please "
pandas/tests/series/test_api.py::TestSeriesMisc::()::test_tab_complete_warning
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/IPython/core/interactiveshell.py:763: UserWarning: Attempting to work in a virtualenv. If you encounter problems, please install IPython inside the virtualenv.
    warn("Attempting to work in a virtualenv. If you encounter problems, please "
pandas/tests/plotting/test_misc.py::TestDataFramePlots::()::test_parallel_coordinates_with_sorted_labels
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/matplotlib/axes/_base.py:3124: UserWarning: Attempting to set identical left==right results
  in singular transformations; automatically expanding.
  left=0, right=0
    'left=%s, right=%s') % (left, right))
pandas/tests/tslibs/test_parsing.py::TestGuessDatetimeFormat::()::test_guess_datetime_format_with_parseable_formats[20111230-%Y%m%d]
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/dateutil/parser/__init__.py:46: DeprecationWarning: _timelex is a private class and may break without warning, it will be moved and or renamed in future versions.
    warnings.warn(msg, DeprecationWarning)
pandas/tests/tslibs/test_parsing.py::TestGuessDatetimeFormat::()::test_guess_datetime_format_with_parseable_formats[2011-12-30-%Y-%m-%d]
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/dateutil/parser/__init__.py:46: DeprecationWarning: _timelex is a private class and may break without warning, it will be moved and or renamed in future versions.
    warnings.warn(msg, DeprecationWarning)
pandas/tests/tslibs/test_parsing.py::TestGuessDatetimeFormat::()::test_guess_datetime_format_with_parseable_formats[30-12-2011-%d-%m-%Y]
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/dateutil/parser/__init__.py:46: DeprecationWarning: _timelex is a private class and may break without warning, it will be moved and or renamed in future versions.
    warnings.warn(msg, DeprecationWarning)
pandas/tests/tslibs/test_parsing.py::TestGuessDatetimeFormat::()::test_guess_datetime_format_with_parseable_formats[2011-12-30 00:00:00-%Y-%m-%d %H:%M:%S]
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/dateutil/parser/__init__.py:46: DeprecationWarning: _timelex is a private class and may break without warning, it will be moved and or renamed in future versions.
    warnings.warn(msg, DeprecationWarning)
pandas/tests/tslibs/test_parsing.py::TestGuessDatetimeFormat::()::test_guess_datetime_format_with_parseable_formats[2011-12-30T00:00:00-%Y-%m-%dT%H:%M:%S]
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/dateutil/parser/__init__.py:46: DeprecationWarning: _timelex is a private class and may break without warning, it will be moved and or renamed in future versions.
    warnings.warn(msg, DeprecationWarning)
pandas/tests/tslibs/test_parsing.py::TestGuessDatetimeFormat::()::test_guess_datetime_format_with_parseable_formats[2011-12-30 00:00:00.000000-%Y-%m-%d %H:%M:%S.%f]
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/dateutil/parser/__init__.py:46: DeprecationWarning: _timelex is a private class and may break without warning, it will be moved and or renamed in future versions.
    warnings.warn(msg, DeprecationWarning)
pandas/tests/tslibs/test_parsing.py::TestGuessDatetimeFormat::()::test_guess_datetime_format_with_dayfirst[True-%d/%m/%Y]
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/dateutil/parser/__init__.py:46: DeprecationWarning: _timelex is a private class and may break without warning, it will be moved and or renamed in future versions.
    warnings.warn(msg, DeprecationWarning)
pandas/tests/tslibs/test_parsing.py::TestGuessDatetimeFormat::()::test_guess_datetime_format_with_dayfirst[False-%m/%d/%Y]
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/dateutil/parser/__init__.py:46: DeprecationWarning: _timelex is a private class and may break without warning, it will be moved and or renamed in future versions.
    warnings.warn(msg, DeprecationWarning)
pandas/tests/tslibs/test_parsing.py::TestGuessDatetimeFormat::()::test_guess_datetime_format_invalid_inputs
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/dateutil/parser/__init__.py:46: DeprecationWarning: _timelex is a private class and may break without warning, it will be moved and or renamed in future versions.
    warnings.warn(msg, DeprecationWarning)
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/dateutil/parser/__init__.py:46: DeprecationWarning: _timelex is a private class and may break without warning, it will be moved and or renamed in future versions.
    warnings.warn(msg, DeprecationWarning)
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/dateutil/parser/__init__.py:46: DeprecationWarning: _timelex is a private class and may break without warning, it will be moved and or renamed in future versions.
    warnings.warn(msg, DeprecationWarning)
pandas/tests/tslibs/test_parsing.py::TestGuessDatetimeFormat::()::test_guess_datetime_format_nopadding[2011-1-1-%Y-%m-%d]
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/dateutil/parser/__init__.py:46: DeprecationWarning: _timelex is a private class and may break without warning, it will be moved and or renamed in future versions.
    warnings.warn(msg, DeprecationWarning)
pandas/tests/tslibs/test_parsing.py::TestGuessDatetimeFormat::()::test_guess_datetime_format_nopadding[30-1-2011-%d-%m-%Y]
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/dateutil/parser/__init__.py:46: DeprecationWarning: _timelex is a private class and may break without warning, it will be moved and or renamed in future versions.
    warnings.warn(msg, DeprecationWarning)
pandas/tests/tslibs/test_parsing.py::TestGuessDatetimeFormat::()::test_guess_datetime_format_nopadding[1/1/2011-%m/%d/%Y]
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/dateutil/parser/__init__.py:46: DeprecationWarning: _timelex is a private class and may break without warning, it will be moved and or renamed in future versions.
    warnings.warn(msg, DeprecationWarning)
pandas/tests/tslibs/test_parsing.py::TestGuessDatetimeFormat::()::test_guess_datetime_format_nopadding[2011-1-1 00:00:00-%Y-%m-%d %H:%M:%S]
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/dateutil/parser/__init__.py:46: DeprecationWarning: _timelex is a private class and may break without warning, it will be moved and or renamed in future versions.
    warnings.warn(msg, DeprecationWarning)
pandas/tests/tslibs/test_parsing.py::TestGuessDatetimeFormat::()::test_guess_datetime_format_nopadding[2011-1-1 0:0:0-%Y-%m-%d %H:%M:%S]
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/dateutil/parser/__init__.py:46: DeprecationWarning: _timelex is a private class and may break without warning, it will be moved and or renamed in future versions.
    warnings.warn(msg, DeprecationWarning)
pandas/tests/tslibs/test_parsing.py::TestGuessDatetimeFormat::()::test_guess_datetime_format_nopadding[2011-1-3T00:00:0-%Y-%m-%dT%H:%M:%S]
  /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/dateutil/parser/__init__.py:46: DeprecationWarning: _timelex is a private class and may break without warning, it will be moved and or renamed in future versions.
    warnings.warn(msg, DeprecationWarning)
pandas/tests/scalar/timestamp/test_timezones.py::TestTimestampTZOperations::()::test_tz_localize_pushes_out_of_bounds
  /home/travis/build/pandas-dev/pandas/pandas/tests/scalar/timestamp/test_timezones.py:32: RuntimeWarning: overflow encountered in long_scalars
    Timestamp.min.tz_localize('Asia/Tokyo')
  /home/travis/build/pandas-dev/pandas/pandas/tests/scalar/timestamp/test_timezones.py:39: RuntimeWarning: overflow encountered in long_scalars
    Timestamp.max.tz_localize('US/Pacific')
-- Docs: http://doc.pytest.org/en/latest/warnings.html
 24703 passed, 1037 skipped, 79 xfailed, 31 xpassed, 53 warnings in 824.37 seconds 
/home/travis/build/pandas-dev/pandas/pandas/core/strings.py:257: DeprecationWarning: invalid escape sequence \$
  """
/home/travis/build/pandas-dev/pandas/pandas/core/strings.py:382: DeprecationWarning: invalid escape sequence \d
  """
```