BUG: in Python3 MultiIndex.from_tuples cannot take "zipped" tuples · Issue #18434 · pandas-dev/pandas (original) (raw)

Code Sample, a copy-pastable example if possible

This code fails in python 3

import pandas as pd my_index = pd.MultiIndex.from_tuples(zip(['a', 'b'], ['c', 'd'], ['e', 'f']), names=['A','B', 'C'])

Problem description

The code above gives an Exception

TypeError: object of type 'zip' has no len()

Because in python3, unlike in python2, the return from zip is NOT a list and cannot get length.

In pandas, there are multiple instances in MultiIndex and related classes, where the code tries to get len() from the arguments, which are valid input but no longer have len property in python3.

Expected Output

Same as in python2
In the case above, should be

MultiIndex(levels=[['a', 'b'], ['c', 'd'], ['e', 'f']], labels=[[0, 1], [0, 1], [0, 1]], names=['A', 'B', 'C'])

Output of pd.show_versions()

INSTALLED VERSIONS

commit: None
python: 3.6.3.final.0
python-bits: 64
OS: Darwin
OS-release: 16.7.0
machine: x86_64
processor: i386
byteorder: little
LC_ALL: None
LANG: en_US.UTF-8
LOCALE: en_US.UTF-8

pandas: 0.21.0
pytest: None
pip: 9.0.1
setuptools: 36.5.0
Cython: None
numpy: 1.13.3
scipy: 1.0.0
pyarrow: None
xarray: None
IPython: 6.0.0
sphinx: None
patsy: 0.4.1
dateutil: 2.6.1
pytz: 2017.3
blosc: None
bottleneck: None
tables: 3.4.2
numexpr: 2.6.4
feather: None
matplotlib: 2.0.2
openpyxl: None
xlrd: None
xlwt: None
xlsxwriter: None
lxml: None
bs4: None
html5lib: None
sqlalchemy: None
pymysql: None
psycopg2: None
jinja2: None
s3fs: None
fastparquet: None
pandas_gbq: None
pandas_datareader: None