Stacking with MultiIndex column DataFrame throws an error #3170
Description
Stacking this particular MultiIndex column DataFrame throws an error:
import pandas as pd
from StringIO import StringIO
csv = StringIO("""ID,NAME,DATE,VAR1
1,a,03-JAN-2013,69
1,a,04-JAN-2013,77
1,a,05-JAN-2013,75
2,b,03-JAN-2013,69
2,b,04-JAN-2013,75
2,b,05-JAN-2013,72""")
df = pd.read_csv(csv, index_col=['DATE', 'ID'], parse_dates=['DATE'])
df.columns.name = 'Params'
In [11]: df.unstack('ID').resample('W-THU')
Out[11]:
Params VAR1
ID 1 2
DATE
2013-01-03 69 69.0
2013-01-10 76 73.5
It looks like you ought to be able to stack this over 'ID', but it throws an error:
In [12]: df.unstack('ID').resample('W-THU').stack('ID')
---------------------------------------------------------------------------
IndexError Traceback (most recent call last)
<ipython-input-12-e61b475b7bed> in <module>()
----> 1 df.unstack('ID').resample('W-THU').stack('ID')
/Library/Python/2.7/site-packages/pandas/core/frame.pyc in stack(self, level, dropna)
3950 return result
3951 else:
-> 3952 return stack(self, level, dropna=dropna)
3953
3954 def unstack(self, level=-1):
/Library/Python/2.7/site-packages/pandas/core/reshape.pyc in stack(frame, level, dropna)
443
444 if isinstance(frame.columns, MultiIndex):
--> 445 return _stack_multi_columns(frame, level=level, dropna=True)
446 elif isinstance(frame.index, MultiIndex):
447 new_levels = list(frame.index.levels)
/Library/Python/2.7/site-packages/pandas/core/reshape.pyc in _stack_multi_columns(frame, level, dropna)
504 # can make more efficient?
505 if loc.stop - loc.start != levsize:
--> 506 chunk = this.ix[:, this.columns[loc]]
507 chunk.columns = level_vals.take(chunk.columns.labels[-1])
508 value_slice = chunk.reindex(columns=level_vals).values
/Library/Python/2.7/site-packages/pandas/core/indexing.pyc in __getitem__(self, key)
32 pass
33
---> 34 return self._getitem_tuple(key)
35 else:
36 return self._getitem_axis(key, axis=0)
/Library/Python/2.7/site-packages/pandas/core/indexing.pyc in _getitem_tuple(self, tup)
222 continue
223
--> 224 retval = retval.ix._getitem_axis(key, axis=i)
225
226 return retval
/Library/Python/2.7/site-packages/pandas/core/indexing.pyc in _getitem_axis(self, key, axis)
340 raise ValueError('Cannot index with multidimensional key')
341
--> 342 return self._getitem_iterable(key, axis=axis)
343 elif axis == 0:
344 is_int_index = _is_integer_index(labels)
/Library/Python/2.7/site-packages/pandas/core/indexing.pyc in _getitem_iterable(self, key, axis)
406 # this is not the most robust, but...
407 if (isinstance(labels, MultiIndex) and
--> 408 not isinstance(keyarr[0], tuple)):
409 level = 0
410 else:
/Library/Python/2.7/site-packages/pandas/core/index.pyc in __getitem__(self, key)
1745 retval = []
1746 for lev, lab in zip(self.levels, self.labels):
-> 1747 if lab[key] == -1:
1748 retval.append(np.nan)
1749 else:
IndexError: index out of bounds
Taken from this SO question.