ERR: disallow non-hashables in Index construction & rename · Issue #20527 · pandas-dev/pandas (original) (raw)

from pandas import Index, DataFrame

df = DataFrame(index=Index([1, 2, 3, 4]), columns=['A', 'B']) df.index.rename(['foo'], inplace=True) df.reset_index()

---

TypeError Traceback (most recent call last)
in ()
----> 5 df.reset_index()

c:\program files\python36\lib\site-packages\pandas\core\frame.py in reset_index(self, level, drop, inplace, col_level, col_fill)
3377 # to ndarray and maybe infer different dtype
3378 level_values = _maybe_casted_values(lev, lab)
-> 3379 new_obj.insert(0, name, level_values)
3380
3381 new_obj.index = new_index

c:\program files\python36\lib\site-packages\pandas\core\frame.py in insert(self, loc, column, value, allow_duplicates)
2611 value = self._sanitize_column(column, value, broadcast=False)
2612 self._data.insert(loc, column, value,
-> 2613 allow_duplicates=allow_duplicates)
2614
2615 def assign(self, **kwargs):

c:\program files\python36\lib\site-packages\pandas\core\internals.py in insert(self, loc, item, value, allow_duplicates)
4059
4060 """
-> 4061 if not allow_duplicates and item in self.items:
4062 # Should this be a different kind of error??
4063 raise ValueError('cannot insert {}, already exists'.format(item))

c:\program files\python36\lib\site-packages\pandas\core\indexes\base.py in contains(self, key)
1692 @appender(_index_shared_docs['contains'] % _index_doc_kwargs)
1693 def contains(self, key):
-> 1694 hash(key)
1695 try:
1696 return key in self._engine

TypeError: unhashable type: 'list'

Problem description

It think it is reasonable to expect Index([1, 2, 3, 4]).rename(['foo']) and Index([1, 2, 3, 4]).rename('foo') resulting in the same, however this is not the case.

Probably this line be modified in Index.rename:

- return self.set_names([name], inplace=inplace)
+ return self.set_names(name, inplace=inplace)

Expected Output

Index([1, 2, 3, 4]).rename(['foo']) Int64Index([1, 2, 3, 4], dtype='int64', name='foo')

Output of pd.show_versions()

INSTALLED VERSIONS

commit: None
python: 3.6.3.final.0
python-bits: 64
OS: Windows
OS-release: 10
machine: AMD64
processor: Intel64 Family 6 Model 142 Stepping 9, GenuineIntel
byteorder: little
LC_ALL: None
LANG: None
LOCALE: None.None

pandas: 0.22.0
pytest: None
pip: 9.0.1
setuptools: 28.8.0
Cython: None
numpy: 1.14.1
scipy: None
pyarrow: None
xarray: None
IPython: 6.2.1
sphinx: None
patsy: None
dateutil: 2.6.1
pytz: 2018.3
blosc: None
bottleneck: None
tables: None
numexpr: None
feather: None
matplotlib: None
openpyxl: None
xlrd: None
xlwt: None
xlsxwriter: None
lxml: None
bs4: None
html5lib: 1.0.1
sqlalchemy: None
pymysql: None
psycopg2: None
jinja2: 2.10
s3fs: None
fastparquet: None
pandas_gbq: None
pandas_datareader: None