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Description
I noticed a bunch of failing tests in a library I'm maintaining when I moved my CI to numpy 2+.
I was relying on python-quantities, and I was making use of __imul__, __iadd__, etc.
I guess I (we) didn't quite get the semantics right for array wrapping for numpy>=2.
Here's a reproducer:
import quantities as pq
velocity = 3 * pq.m/pq.s
time = 2*pq.s
distance = velocity.copy()
distance *= time # <--- this is the problematic part, if we write distance = distance * time, things work as expected even using numpy>=2
n_centimeters = distance.rescale(pq.centimeter)
print(n_centimeters)
n_cm_ul = n_centimeters.magnitude.item()
assert isinstance(n_cm_ul, float)
err = n_cm_ul - 300*2
print(f"{err=}")
assert abs(err) < 1e-12Executing it with numpy 1.26.4 and numpy 2+:
(cpython-v3.13-apt-deb) 13:38 root@argus:/home/bjorn/vc/chempy# python regression_quantities2.py
600.0 cm
err=0.0
(cpython-v3.13-apt-deb) 13:38 root@argus:/home/bjorn/vc/chempy# pip install 'numpy>2'
Collecting numpy>2
Downloading numpy-2.3.1-cp313-cp313-manylinux_2_28_x86_64.whl.metadata (62 kB)
Downloading numpy-2.3.1-cp313-cp313-manylinux_2_28_x86_64.whl (16.6 MB)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 16.6/16.6 MB 48.0 MB/s eta 0:00:00
Installing collected packages: numpy
Attempting uninstall: numpy
Found existing installation: numpy 1.26.4
Uninstalling numpy-1.26.4:
Successfully uninstalled numpy-1.26.4
Successfully installed numpy-2.3.1
(cpython-v3.13-apt-deb) 13:38 root@argus:/home/bjorn/vc/chempy# python regression_quantities2.py
Traceback (most recent call last):
File "/opt-3/cpython-v3.13-apt-deb/lib/python3.13/site-packages/quantities/quantity.py", line 216, in rescale
cf = get_conversion_factor(from_u, to_u)
File "/opt-3/cpython-v3.13-apt-deb/lib/python3.13/site-packages/quantities/quantity.py", line 52, in get_conversion_factor
assert from_u.dimensionality == to_u.dimensionality
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/home/bjorn/vc/chempy/regression_quantities2.py", line 6, in <module>
n_centimeters = distance.rescale(pq.centimeter)
File "/opt-3/cpython-v3.13-apt-deb/lib/python3.13/site-packages/quantities/quantity.py", line 218, in rescale
raise ValueError(
...<2 lines>...
)
ValueError: Unable to convert between units of "m/s" and "cm"
As a work around, I have changed all my call sites from expressions of the form:
my_dict[key] *= otherto:
my_dict[key] = my_dict[key] * other # <--- works with current released quantities & numpy>=2Metadata
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