ValueError Traceback (most recent call last) <ipython-input-35-f9a275b6ce2c> in <module>() ----> 1 pd.Series([1, 1], index=[True, False]).drop(True) /home/d/.virtualenvs/test/local/lib/python2.7/site-packages/pandas-0.15.0rc1-py2.7-linux-x86_64.egg/pandas/core/generic.pyc in drop(self, labels, axis, level, inplace, **kwargs) 1531 axis, axis_ = self._get_axis(axis), axis 1532 -> 1533 if axis.is_unique: 1534 if level is not None: 1535 if not isinstance(axis, MultiIndex): /home/d/.virtualenvs/test/local/lib/python2.7/site-packages/pandas-0.15.0rc1-py2.7-linux-x86_64.egg/pandas/lib.so in pandas.lib.cache_readonly.__get__ (pandas/lib.c:38943)() /home/d/.virtualenvs/test/local/lib/python2.7/site-packages/pandas-0.15.0rc1-py2.7-linux-x86_64.egg/pandas/core/index.pyc in is_unique(self) 582 def is_unique(self): 583 """ return if the index has unique values """ --> 584 return self._engine.is_unique 585 586 def is_integer(self): /home/d/.virtualenvs/test/local/lib/python2.7/site-packages/pandas-0.15.0rc1-py2.7-linux-x86_64.egg/pandas/index.so in pandas.index.IndexEngine.is_unique.__get__ (pandas/index.c:4449)() /home/d/.virtualenvs/test/local/lib/python2.7/site-packages/pandas-0.15.0rc1-py2.7-linux-x86_64.egg/pandas/index.so in pandas.index.IndexEngine._do_unique_check (pandas/index.c:4901)() /home/d/.virtualenvs/test/local/lib/python2.7/site-packages/pandas-0.15.0rc1-py2.7-linux-x86_64.egg/pandas/index.so in pandas.index.IndexEngine._ensure_mapping_populated (pandas/index.c:5106)() /home/d/.virtualenvs/test/local/lib/python2.7/site-packages/pandas-0.15.0rc1-py2.7-linux-x86_64.egg/pandas/index.so in pandas.index.IndexEngine.initialize (pandas/index.c:5203)() /home/d/.virtualenvs/test/local/lib/python2.7/site-packages/pandas-0.15.0rc1-py2.7-linux-x86_64.egg/pandas/hashtable.so in pandas.hashtable.PyObjectHashTable.map_locations (pandas/hashtable.c:12440)() ValueError: Does not understand character buffer dtype format string ('?')