dataframe repr broken if unlimited pandas printing is enabled

[orenmazor]

System information

• OS Platform and Distribution (e.g., Linux Ubuntu 16.04): Docker container: python:3.8.3-slim, uname output: Linux bf69e4362f35 4.19.76-linuxkit #1 SMP Tue May 26 11:42:35 UTC 2020 x86_64 GNU/Linux
• Modin version (modin.__version__): initially encountered on 0.7.4, but confirmed on current SHA 37b7d2c4c5b3ac04408f362b3989de30dd3df1a2
• Python version: 3.8.3
• Code we can use to reproduce: see in source code

Describe the problem

I'm only just starting to switch from pandas to modin, so this could be an obvious case. but in case it's not, I figured I'd report this.

if you set_option on max_rows/max_columns to None (unlimited), you encounter a few issues. I think in my case they all stem from this snippet here.

Source code / logs

Python 3.8.3 (default, Jun  9 2020, 17:49:41) 
[GCC 8.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import modin.pandas as pandas
>>> pandas.DataFrame()
UserWarning: Distributing <class 'NoneType'> object. This may take some time.
Empty DataFrame
Columns: []
Index: []
>>> pandas.set_option("display.max_rows", None)
>>> pandas.DataFrame()
UserWarning: Distributing <class 'NoneType'> object. This may take some time.
Empty DataFrame
Columns: []
Index: []
>>> pandas.set_option("display.max_columns", None)
>>> pandas.DataFrame()
UserWarning: Distributing <class 'NoneType'> object. This may take some time.
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/root/.cache/pypoetry/virtualenvs/onepassword-etl-NcjVOHQt-py3.8/src/modin/modin/pandas/dataframe.py", line 151, in __repr__
    col_counter += len(str(self.columns[i])) + 1
  File "/root/.cache/pypoetry/virtualenvs/onepassword-etl-NcjVOHQt-py3.8/lib/python3.8/site-packages/pandas/core/indexes/base.py", line 3930, in __getitem__
    return getitem(key)
IndexError: index 0 is out of bounds for axis 0 with size 0
>>> ```

[devin-petersohn]

Hi @orenmazor thanks for reporting this!

I'll flag the fix for the next release, but it is happening within the next week so it may fall to the release after that. Thanks again for reporting!

[devin-petersohn]

This turned out to be a one line fix 🎉 .

[orenmazor]