AttributeError: np.unicode_ was removed in the NumPy 2.0 release. Use np.str_ instead

[weiji14]

What happened?

We've been getting this AttributeError on PyGMT's dev CI which tests nightly packages of numpy/xarray/etc. See https://github.com/GenericMappingTools/pygmt/actions/runs/6043991082/job/16401918043#step:16:40

What did you expect to happen?

Running import xarray as xr should work with numpy 2.0.

Minimal Complete Verifiable Example

mamba create --name xr_with_np2 python=3.11
mamba activate xr_with_np2
python -m pip install --pre --extra-index https://pypi.anaconda.org/scientific-python-nightly-wheels/simple numpy pandas xarray

python -c "import xarray as xr"

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.

Relevant log output

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/home/user/mambaforge/envs/xr_with_np2/lib/python3.11/site-packages/xarray/__init__.py", line 1, in <module>
    from xarray import testing, tutorial
  File "/home/user/mambaforge/envs/xr_with_np2/lib/python3.11/site-packages/xarray/testing.py", line 10, in <module>
    from xarray.core import duck_array_ops, formatting, utils
  File "/home/user/mambaforge/envs/xr_with_np2/lib/python3.11/site-packages/xarray/core/duck_array_ops.py", line 36, in <module>
    from xarray.core import dask_array_ops, dtypes, nputils
  File "/home/user/mambaforge/envs/xr_with_np2/lib/python3.11/site-packages/xarray/core/dask_array_ops.py", line 3, in <module>
    from xarray.core import dtypes, nputils
  File "/home/user/mambaforge/envs/xr_with_np2/lib/python3.11/site-packages/xarray/core/dtypes.py", line 43, in <module>
    (np.bytes_, np.unicode_),  # numpy promotes to unicode
                ^^^^^^^^^^^
  File "/home/user/mambaforge/envs/xr_with_np2/lib/python3.11/site-packages/numpy/__init__.py", line 372, in __getattr__
    raise AttributeError(
AttributeError: `np.unicode_` was removed in the NumPy 2.0 release. Use `np.str_` instead.

Anything else we need to know?

See https://numpy.org/devdocs/release/2.0.0-notes.html#numpy-2-0-python-api-removals. Relevant code at xarray is here

xarray/xarray/core/dtypes.py

Lines 36 to 44 in 1043a9e

	# Pairs of types that, if both found, should be promoted to object dtype
	# instead of following NumPy's own type-promotion rules. These type promotion
	# rules match pandas instead. For reference, see the NumPy type hierarchy:
	# https://numpy.org/doc/stable/reference/arrays.scalars.html
	PROMOTE_TO_OBJECT: tuple[tuple[type[np.generic], type[np.generic]], ...] = (
	(np.number, np.character), # numpy promotes to character
	(np.bool_, np.character), # numpy promotes to character
	(np.bytes_, np.unicode_), # numpy promotes to unicode
	)

Environment

# packages in environment at /home/weiji/mambaforge/envs/xr_with_np2:
#
# Name                    Version                   Build  Channel
_libgcc_mutex             0.1                 conda_forge    conda-forge
_openmp_mutex             4.5                       2_gnu    conda-forge
bzip2                     1.0.8                h7f98852_4    conda-forge
ca-certificates           2023.7.22            hbcca054_0    conda-forge
ld_impl_linux-64          2.40                 h41732ed_0    conda-forge
libexpat                  2.5.0                hcb278e6_1    conda-forge
libffi                    3.4.2                h7f98852_5    conda-forge
libgcc-ng                 13.1.0               he5830b7_0    conda-forge
libgomp                   13.1.0               he5830b7_0    conda-forge
libnsl                    2.0.0                h7f98852_0    conda-forge
libsqlite                 3.43.0               h2797004_0    conda-forge
libuuid                   2.38.1               h0b41bf4_0    conda-forge
libzlib                   1.2.13               hd590300_5    conda-forge
ncurses                   6.4                  hcb278e6_0    conda-forge
numpy                     2.0.0.dev0               pypi_0    pypi
openssl                   3.1.2                hd590300_0    conda-forge
packaging                 23.1                     pypi_0    pypi
pandas                    2.2.0.dev0+141.g413d92d471          pypi_0    pypi
pip                       23.2.1             pyhd8ed1ab_0    conda-forge
python                    3.11.5          hab00c5b_0_cpython    conda-forge
python-dateutil           2.8.2                    pypi_0    pypi
pytz                      2023.3                   pypi_0    pypi
readline                  8.2                  h8228510_1    conda-forge
setuptools                68.1.2             pyhd8ed1ab_0    conda-forge
six                       1.16.0                   pypi_0    pypi
tk                        8.6.12               h27826a3_0    conda-forge
tzdata                    2023.3                   pypi_0    pypi
wheel                     0.41.2             pyhd8ed1ab_0    conda-forge
xarray                    2023.8.1.dev7+g1043a9e1          pypi_0    pypi
xz                        5.2.6                h166bdaf_0    conda-forge

[kmuehlbauer]

@weiji14 Thanks for the report. This is worked on in #8117.