BUG: Column indexing does not work in this case

[socheon]

I am using Pandas 0.13.0rc1-23-g286811a, Python 2.7 and Windows XP.

The space in column names is apparently causing a problem. On IPython,

df = pd.DataFrame(columns=['a', 'b', 'c c'])
df['d'] = 3
df['c c']

Error

C:\python_envs\prod2\lib\site-packages\pandas\core\frame.pyc in __getitem__(self, key)
   1626             return self._getitem_multilevel(key)
   1627         else:
-> 1628             return self._getitem_column(key)
   1629
   1630     def _getitem_column(self, key):

C:\python_envs\prod2\lib\site-packages\pandas\core\frame.pyc in _getitem_column(self, key)
   1633         # get column
   1634         if self.columns.is_unique:
-> 1635             return self._get_item_cache(key)
   1636
   1637         # duplicate columns & possible reduce dimensionaility

C:\python_envs\prod2\lib\site-packages\pandas\core\generic.pyc in _get_item_cache(self, item)
    977         if res is None:
    978             values = self._data.get(item)
--> 979             res = self._box_item_values(item, values)
    980             cache[item] = res
    981             res._cacher = (item, weakref.ref(self))

C:\python_envs\prod2\lib\site-packages\pandas\core\frame.pyc in _box_item_values(self, key, values)
   1834             return self._constructor(values.T, columns=items, index=self.index)
   1835         else:
-> 1836             return self._box_col_values(values, items)
   1837
   1838     def _box_col_values(self, values, items):

C:\python_envs\prod2\lib\site-packages\pandas\core\frame.pyc in _box_col_values(self, values, items)
   1839         """ provide boxed values for a column """
   1840         return self._constructor_sliced.from_array(values, index=self.index,
-> 1841                                                    name=items, fastpath=True)
   1842
   1843     def __setitem__(self, key, value):

C:\python_envs\prod2\lib\site-packages\pandas\core\series.pyc in from_array(cls, arr, index, name, copy, fastpath)
    233             cls = SparseSeries
    234
--> 235         return cls(arr, index=index, name=name, copy=copy, fastpath=fastpath)
    236
    237     @property

C:\python_envs\prod2\lib\site-packages\pandas\core\series.pyc in __init__(self, data, index, dtype, name, copy, fastpath
)
    130             # data is an ndarray, index is defined
    131             if not isinstance(data, SingleBlockManager):
--> 132                 data = SingleBlockManager(data, index, fastpath=True)
    133             if copy:
    134                 data = data.copy()

C:\python_envs\prod2\lib\site-packages\pandas\core\internals.pyc in __init__(self, block, axis, do_integrity_check, fast
path)
   3413                 block = block[0]
   3414             if not isinstance(block, Block):
-> 3415                 block = make_block(block, axis, axis, ndim=1, fastpath=True)
   3416
   3417         else:

C:\python_envs\prod2\lib\site-packages\pandas\core\internals.pyc in make_block(values, items, ref_items, klass, ndim, dt
ype, fastpath, placement)
   1893
   1894     return klass(values, items, ref_items, ndim=ndim, fastpath=fastpath,
-> 1895                  placement=placement)
   1896
   1897

C:\python_envs\prod2\lib\site-packages\pandas\core\internals.pyc in __init__(self, values, items, ref_items, ndim, fastp
ath, placement)
   1297         super(ObjectBlock, self).__init__(values, items, ref_items, ndim=ndim,
   1298                                           fastpath=fastpath,
-> 1299                                           placement=placement)
   1300
   1301     @property

C:\python_envs\prod2\lib\site-packages\pandas\core\internals.pyc in __init__(self, values, items, ref_items, ndim, fastp
ath, placement)
     63         if len(items) != len(values):
     64             raise ValueError('Wrong number of items passed %d, indices imply '
---> 65                              '%d' % (len(items), len(values)))
     66
     67         self.set_ref_locs(placement)

ValueError: Wrong number of items passed 1, indices imply 0

[jreback]

this may not be doing what you expect, with current master
(this was just fixed very recently via #5723)

You setting with a scalar when their is no index, does not work (hmm...maybe I should raise on this)

In [1]: df = pd.DataFrame(columns=['a', 'b', 'c c'])

In [2]: df
Out[2]: 
Empty DataFrame
Columns: [a, b, c c]
Index: []

[0 rows x 3 columns]

This will now raise

In [3]: df['d'] = 3

Selection works fine

In [4]: df
Out[4]: 
Empty DataFrame
Columns: [a, b, c c]
Index: []

[0 rows x 4 columns]

In [5]: df['c c']
Out[5]: Series([], name: c c, dtype: object)

In [6]: pd.__version__
Out[6]: '0.13.0rc1-99-gbac7c6e'

[socheon]

Thanks for the fix! After upgrading, it works fine now.