Modin Pandas concat with axis=1 does not work

[pashkov-v]

System information

• OS Platform and Distribution (e.g., Linux Ubuntu 16.04): Ubuntu 18.04.4 LTS
• Modin version (modin.__version__): 0.7.4
• Python version: 3.8.0

Describe the problem

When I try to concatenate several Modin Pandas DataFrames of equal number of rows column-wise, I get either KeyError: 'Passing list-likes to .loc or [] with any missing labels is no longer supported, see https://pandas.pydata.org/pandas-docs/stable/user_guide/indexing.html#deprecate-loc-reindex-listlike' (when ignore_index=False), or ValueError: Length mismatch: (with ignore_index=True).

Source code / logs

import numpy as np
import modin.pandas as modin_pd
modin_pd.concat([modin_pd.Series(np.ones(10)), modin_pd.Series(np.ones(10))], axis=1, ignore_index=True)

[devin-petersohn]

Hi @pashkov-v thanks for the report!

I can reproduce this with the code you provided on current master branch. It looks like a metadata issue at the API layer because _to_pandas on the result produces a correct result.

import numpy as np
import modin.pandas as modin_pd
modin_pd.concat([modin_pd.Series(np.ones(10)), modin_pd.Series(np.ones(10))], axis=1, ignore_index=True)._to_pandas()