Error on import, pandas incompatibility?

Hello,

Today I noticed that I get an error when importing corner:

import corner

returns

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/mdecleir/opt/anaconda3/envs/astroconda/lib/python3.7/site-packages/corner/__init__.py", line 6, in <module>
    from .corner import corner
  File "/Users/mdecleir/opt/anaconda3/envs/astroconda/lib/python3.7/site-packages/corner/corner.py", line 12, in <module>
    from .arviz_corner import arviz_corner
  File "/Users/mdecleir/opt/anaconda3/envs/astroconda/lib/python3.7/site-packages/corner/arviz_corner.py", line 9, in <module>
    from arviz.data import convert_to_dataset
  File "/Users/mdecleir/opt/anaconda3/envs/astroconda/lib/python3.7/site-packages/arviz/__init__.py", line 32, in <module>
    from .data import *
  File "/Users/mdecleir/opt/anaconda3/envs/astroconda/lib/python3.7/site-packages/arviz/data/__init__.py", line 2, in <module>
    from .base import CoordSpec, DimSpec, dict_to_dataset, numpy_to_data_array
  File "/Users/mdecleir/opt/anaconda3/envs/astroconda/lib/python3.7/site-packages/arviz/data/base.py", line 10, in <module>
    import xarray as xr
  File "/Users/mdecleir/opt/anaconda3/envs/astroconda/lib/python3.7/site-packages/xarray/__init__.py", line 12, in <module>
    from .core.combine import concat, auto_combine
  File "/Users/mdecleir/opt/anaconda3/envs/astroconda/lib/python3.7/site-packages/xarray/core/combine.py", line 11, in <module>
    from .merge import merge
  File "/Users/mdecleir/opt/anaconda3/envs/astroconda/lib/python3.7/site-packages/xarray/core/merge.py", line 10, in <module>
    PANDAS_TYPES = (pd.Series, pd.DataFrame, pd.Panel)
  File "/Users/mdecleir/opt/anaconda3/envs/astroconda/lib/python3.7/site-packages/pandas/__init__.py", line 244, in __getattr__
    raise AttributeError(f"module 'pandas' has no attribute '{name}'")
AttributeError: module 'pandas' has no attribute 'Panel'

I did not see this error before, and I am wondering whether a recent update to pandas might cause this problem?

[mdecleir]

I think pandas and arviz were up to date, but I saw xarray was updated from 11 to 17…

[OriolAbril]

I haven’t seen any similar report on ArviZ side, which versions did you have installed originally @mdecleir? Do you know them?

Maybe it’s something we could have prevented with more strict version requirements in requirements.txt for arviz (or for xarray)