Unidata
Metpy 1.6.2 seems incompatible with xarray 2024.9.0
What went wrong?
When using metpy 1.6.3 with xarray 2024.9.0, importing metpy fails
I'm building a docker container with this requirements.txt:
numpy
matplotlib
pandas
xarray
metpy
cartopy
requests
cfgrib
eccodes
Until a couple of days ago, my app would work fine. It still builds fine but when I run it it fails as described below. On my desktop with xarray 2024.6.0 and metpy 1.6.2, the app runs fine.
Packages in docker container:
Package Version
------------------ -----------
appdirs 1.4.4
attrs 24.2.0
Cartopy 0.24.1
certifi 2024.8.30
cffi 1.17.1
cfgrib 0.9.14.1
charset-normalizer 3.4.0
click 8.1.7
contourpy 1.3.0
cycler 0.12.1
eccodes 2.38.1
findlibs 0.0.5
flexcache 0.3
flexparser 0.3.1
fonttools 4.54.1
idna 3.10
kiwisolver 1.4.7
matplotlib 3.9.2
MetPy 1.6.3
numpy 2.1.2
packaging 24.1
pandas 2.2.3
pillow 10.4.0
Pint 0.24.3
pip 24.2
platformdirs 4.3.6
pooch 1.8.2
pycparser 2.22
pyparsing 3.1.4
pyproj 3.7.0
pyshp 2.3.1
python-dateutil 2.9.0.post0
pytz 2024.2
requests 2.32.3
scipy 1.14.1
shapely 2.0.6
six 1.16.0
traitlets 5.14.3
typing_extensions 4.12.2
tzdata 2024.2
urllib3 2.2.3
xarray 2024.9.0
Operating System
Linux
Version
1.6.3
Python Version
3.13.0
Code to Reproduce
import metpy.calc as mpcalc from metpy.units import units
Errors, Traceback, and Logs
Traceback (most recent call last):
File "/app/main.py", line 2, in
import functions as func
File "/app/functions.py", line 5, in
import metpy.calc as mpcalc
File "/venv/lib/python3.13/site-packages/metpy/init.py", line 13, in
from .xarray import * # noqa: F401, F403, E402
^^^^^^^^^^^^^^^^^^^^^
File "/venv/lib/python3.13/site-packages/metpy/xarray.py", line 31, in
from .units import (_mutate_arguments, DimensionalityError, is_quantity, UndefinedUnitError,
units)
File "/venv/lib/python3.13/site-packages/metpy/units.py", line 26, in
import pint
File "/venv/lib/python3.13/site-packages/pint/init.py", line 18, in
from .delegates.formatter._format_helpers import formatter
File "/venv/lib/python3.13/site-packages/pint/delegates/init.py", line 12, in
from . import txt_defparser
File "/venv/lib/python3.13/site-packages/pint/delegates/txt_defparser/init.py", line 12, in
from .defparser import DefParser
File "/venv/lib/python3.13/site-packages/pint/delegates/txt_defparser/defparser.py", line 10, in
from . import block, common, context, defaults, group, plain, system
File "/venv/lib/python3.13/site-packages/pint/delegates/txt_defparser/common.py", line 23, in
@dataclass(frozen=True)
~~~~~~~~~^^^^^^^^^^^^^
File "/usr/local/lib/python3.13/dataclasses.py", line 1295, in wrap
return _process_class(cls, init, repr, eq, order, unsafe_hash,
frozen, match_args, kw_only, slots,
weakref_slot)
File "/usr/local/lib/python3.13/dataclasses.py", line 1043, in _process_class
raise TypeError('cannot inherit frozen dataclass from a '
'non-frozen one')
TypeError: cannot inherit frozen dataclass from a non-frozen one
Actually, it seems, the problem is Python 3.13. After some more debugging, my application seems to run fine with latest metpy and latest xarray under Python 3.12.7
Related question: what happens if you run import pint in the python environment where your app fails, without attempting to import MetPy or XArray? That appears three lines down from the MetPy import.
EDIT: reasoning: it looks like the problem is a conflict between pint and Python 3.13
Yes, this is a known problem with pint on Python 3.13. I'm going to try to dig in further when I have the cycles. The only work-around right now is to use Python < 3.13.
Pint has released 0.24.4 (needing flexparser 0.4) that fixes this and allows Python 3.13 to work.