DataArray types must be strings

[maresb]

What happened?

While trying to understand the way dimensions are typed in namedarray I was confused by the requirement that dimension names must be strings:

>>> da = xr.DataArray(data=[1,2,3], dims=[7])
TypeError: dimension 7 is not a string

However, the type hints suggest that dimension names can more generally be Hashable. According to @headtr1ck's post, the desired behavior is that Hashable dimension names should be allowed, so this TypeError may be considered a bug.

What did you expect to happen?

No response

Minimal Complete Verifiable Example

No response

MVCE confirmation

• Minimal example — the example is as focused as reasonably possible to demonstrate the underlying issue in xarray.
• Complete example — the example is self-contained, including all data and the text of any traceback.
• Verifiable example — the example copy & pastes into an IPython prompt or Binder notebook, returning the result.
• New issue — a search of GitHub Issues suggests this is not a duplicate.
• Recent environment — the issue occurs with the latest version of xarray and its dependencies.

Relevant log output

No response

Anything else we need to know?

No response

Environment

INSTALLED VERSIONS

commit: None
python: 3.11.6 | packaged by conda-forge | (main, Oct 3 2023, 10:40:35) [GCC 12.3.0]
python-bits: 64
OS: Linux
OS-release: 5.15.0-89-generic
machine: x86_64
processor: x86_64
byteorder: little
LC_ALL: C.UTF-8
LANG: C.UTF-8
LOCALE: ('en_US', 'UTF-8')
libhdf5: 1.14.2
libnetcdf: 4.9.2

xarray: 2023.11.0
pandas: 1.5.3
numpy: 1.26.2
scipy: 1.11.4
netCDF4: 1.6.5
pydap: None
h5netcdf: 1.3.0
h5py: 3.10.0
Nio: None
zarr: 2.16.1
cftime: 1.6.3
nc_time_axis: None
iris: None
bottleneck: None
dask: 2023.11.0
distributed: 2023.11.0
matplotlib: 3.8.2
cartopy: 0.22.0
seaborn: 0.13.0
numbagg: None
fsspec: 2023.10.0
cupy: None
pint: None
sparse: 0.14.0
flox: 0.8.3
numpy_groupies: 0.10.2
setuptools: 68.2.2
pip: 23.3.1
conda: 23.10.0
pytest: 7.4.3
mypy: 1.7.1
IPython: 8.18.0
sphinx: None
/opt/conda/lib/python3.11/site-packages/_distutils_hack/init.py:33: UserWarning: Setuptools is replacing distutils.
warnings.warn("Setuptools is replacing distutils.")

[welcome]

Thanks for opening your first issue here at xarray! Be sure to follow the issue template!
If you have an idea for a solution, we would really welcome a Pull Request with proposed changes.
See the Contributing Guide for more.
It may take us a while to respond here, but we really value your contribution. Contributors like you help make xarray better.
Thank you!

[max-sixty]

Yes, I'm not sure why that check is there. Probably it should be replaced with a check for Hashable — at least we could make the change that and confirm nothing breaks.

PRs welcome!

Notably it is possible to make a Dataset with a non-string dim name:

xr.Dataset(dict(x=((7,),[1,2,3])))
Out[4]:
<xarray.Dataset>
Dimensions:  (7: 3)
Dimensions without coordinates: 7
Data variables:
    x        (7) int64 1 2 3