Importing issue of xarray when using numpy 1.21

[TiemoMathijssen]

After installing numpy v1.21, I have a problem importing xarray 0.18.2 in python3.7.9. This problem does not occur using numpy v1.20.3.

Steps to reproduce:

Numpy and xarray libraries are installed using pip3 install

Error message:

Python 3.7.9 (default, Apr 30 2021, 20:11:56)
[GCC 7.3.1 20180712 (Red Hat 7.3.1-12)] on linux
Type "help", "copyright", "credits" or "license" for more information.

        import xarray
        Traceback (most recent call last):
        File "", line 1, in
        File "/home/rainbow/.local/lib/python3.7/site-packages/xarray/init.py", line 3, in
        from . import testing, tutorial, ufuncs
        File "/home/rainbow/.local/lib/python3.7/site-packages/xarray/testing.py", line 8, in
        from xarray.core import duck_array_ops, formatting, utils
        File "/home/rainbow/.local/lib/python3.7/site-packages/xarray/core/duck_array_ops.py", line 16, in
        from . import dask_array_compat, dask_array_ops, dtypes, npcompat, nputils
        File "/home/rainbow/.local/lib/python3.7/site-packages/xarray/core/npcompat.py", line 81, in
        from numpy.typing import ArrayLike, DTypeLike
        File "/home/rainbow/.local/lib/python3.7/site-packages/numpy/typing/init.py", line 315, in
        from ._shape import _Shape, _ShapeLike
        File "/home/rainbow/.local/lib/python3.7/site-packages/numpy/typing/_shape.py", line 15, in
        _ShapeLike = Union[SupportsIndex, Sequence[SupportsIndex]]
        File "/usr/lib64/python3.7/typing.py", line 254, in inner
        return func(*args, **kwds)
        File "/usr/lib64/python3.7/typing.py", line 634, in getitem
        params = tuple(_type_check(p, msg) for p in params)
        File "/usr/lib64/python3.7/typing.py", line 634, in
        params = tuple(_type_check(p, msg) for p in params)
        File "/usr/lib64/python3.7/typing.py", line 142, in _type_check
        raise TypeError(f"{msg} Got {arg!r:.100}.")
        TypeError: Parameters to generic types must be types. Got NotImplemented.

[shoyer]

What happens if you write from numpy.typing import ArrayLike, DTypeLike without using Xarray at all? This looks a like it may be a NumPy installation issue, not directly related to Xarray.

[TiemoMathijssen]

It is indeed a Numpy issue that occurs with python 3.7. I have posted the same issue on numpy/numpy#19310.

Quote:
"A fix for the issue is currently up at #19311 and should be in the next release.

In the meantime there two possible ways of remedying the situation:

Upgrade to python >=3.8.
Install typing-extensions.

"

[max-sixty]

Thanks @TiemoMathijssen . Closing this