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BaseFloat._check_scalar does not properly check string values #3586
Description
Zarr version
commit edd47db
Numcodecs version
Python Version
3.13.3
Operating System
Linux
Installation
uv dev
Description
uv run python
Python 3.13.3 (main, Apr 9 2025, 04:03:52) [Clang 20.1.0 ] on linux
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>>> from zarr.core.dtype.npy.float import Float32
>>> Float32().cast_scalar('NaN')
np.float32(nan)
>>> Float32().cast_scalar('not valid')
Traceback (most recent call last):
File "<python-input-2>", line 1, in <module>
Float32().cast_scalar('not valid')
~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^
File "/zarr-python/src/zarr/core/dtype/npy/float.py", line 237, in cast_scalar
return self._cast_scalar_unchecked(data)
~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^
File "/zarr-python/src/zarr/core/dtype/npy/float.py", line 220, in _cast_scalar_unchecked
return self.to_native_dtype().type(data) # type: ignore[return-value]
~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^
ValueError: could not convert string to float: 'not valid'Notice how the above does not produce a TypeError but a ValueError. I don't think this is intended. This actually lets my tests for a "Subarray" dtype fail (via the invalid_scalar_params field), because I pass the check through to the sub-dtype, i.e. return self.subdtype._check_scalar(data).
Steps to reproduce
See above
Additional output
No response
Activity
d-v-b commentedon Nov 20, 2025
thanks for this report, I agree that we should be raising a
TypeErrorhere.fix: BaseFloat._check_scalar rejects invalid string values (zarr-deve…
fix: BaseFloat._check_scalar rejects invalid string values (zarr-deve…