Series.str.get_dummies fails if one of the categorical variables is called 'name'

[DGrady]

This works as expected:

>>> s = pd.Series(['Name', 'email|Name|address', 'address|email'])
>>> s.str.get_dummies(sep='|')
   Name  address  email
0     1        0      0
1     1        1      1
2     0        1      1

However, if any of the categorical variables is named exactly 'name', then there's a problem.

>>> s = pd.Series(['name', 'email|Name|address', 'address|email'])
>>> s.str.get_dummies(sep='|')
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-5-1a39a6dcd56b> in <module>()
----> 1 s.str.get_dummies(sep='|')

/Users/dgrady/anaconda/envs/python3/lib/python3.5/site-packages/pandas/core/strings.py in get_dummies(self, sep)
   1377         data = self._orig.astype(str) if self._is_categorical else self._data
   1378         result = str_get_dummies(data, sep)
-> 1379         return self._wrap_result(result, use_codes=(not self._is_categorical))
   1380 
   1381     @copy(str_translate)

/Users/dgrady/anaconda/envs/python3/lib/python3.5/site-packages/pandas/core/strings.py in _wrap_result(self, result, use_codes, name)
   1100         if not hasattr(result, 'ndim'):
   1101             return result
-> 1102         name = name or getattr(result, 'name', None) or self._orig.name
   1103 
   1104         if result.ndim == 1:

/Users/dgrady/anaconda/envs/python3/lib/python3.5/site-packages/pandas/core/generic.py in __nonzero__(self)
    729         raise ValueError("The truth value of a {0} is ambiguous. "
    730                          "Use a.empty, a.bool(), a.item(), a.any() or a.all()."
--> 731                          .format(self.__class__.__name__))
    732 
    733     __bool__ = __nonzero__

ValueError: The truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().

This is presumably related to the pandas/core/strings.py code in the stacktrace.

>>> pd.show_versions()

INSTALLED VERSIONS
------------------
commit: None
python: 3.5.1.final.0
python-bits: 64
OS: Darwin
OS-release: 14.5.0
machine: x86_64
processor: i386
byteorder: little
LC_ALL: None
LANG: en_US.UTF-8

pandas: 0.17.1
nose: 1.3.7
pip: 7.1.2
setuptools: 18.5
Cython: 0.23.4
numpy: 1.10.1
scipy: 0.16.0
statsmodels: 0.6.1
IPython: 4.0.1
sphinx: 1.3.1
patsy: 0.4.0
dateutil: 2.4.2
pytz: 2015.7
blosc: None
bottleneck: 1.0.0
tables: 3.2.2
numexpr: 2.4.4
matplotlib: 1.5.0
openpyxl: 2.2.6
xlrd: 0.9.4
xlwt: 1.0.0
xlsxwriter: 0.7.7
lxml: 3.4.4
bs4: 4.4.1
html5lib: None
httplib2: None
apiclient: None
sqlalchemy: 1.0.9
pymysql: None
psycopg2: None
Jinja2: 2.8

[jreback]

I think this is a bug in _wrap_result. The getattr(result,'Name',None) only should be checked if 'name' is in _metadata IOW, its a Series.

[jreback]

@DGrady want to take a crack at it?

[DGrady]

Absolutely — I'll take a look at it later today.