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FLOAT_CMP isn't powerful enough to handle whitespace that is added in fixed-width printing of floats #92
Description
See title. Here's a minimal example with ndarray, where I vary the least significant digit of the element the first row:
>>> import numpy as np
>>> np.array([[0.12345678], [0.11111111]])
array([[0.12345678],
[0.11111111]])
>>> np.array([[0.12345671], [0.11111111]]) # doctest: +FLOAT_CMP
array([[0.12345678],
[0.11111111]])
>>> np.array([[0.12345670], [0.11111111]]) # doctest: +FLOAT_CMP
array([[0.12345678],
[0.11111111]])The second test passes with FLOAT_CMP because the change is well under the relative tolerance.
The third test fails with:
Expected:
array([[0.12345678],
[0.11111111]])
Got:
array([[0.1234567 ],
[0.11111111]])
This failure isn't because of exceeding the tolerance, but rather because of the space between "7" and "]". (I'm hitting this issue with a SkyCoord transformation, where the 32-bit calculation ends in a zero and the 64-bit calculation does not.)
The "obvious" workaround is to turn off FLOAT_CMP and rely on ELLIPSIS to handle the slight discrepancy. But, that could mean adding a lot of ellipsis markers. Is there a better solution?
Activity
ayshih commentedon Dec 20, 2019
I could change the NumPy printing. First setup with:
and then teardown with:
I'll have to mull over whether that's a better workaround.
bsipocz commentedon Dec 20, 2019
ideally
NORMALIZE_WHITESPACEshould take care of this, I think. So likely this may be a bug?ayshih commentedon Dec 20, 2019
I guess it's technically out of the scope of
NORMALIZE_WHITESPACEbecause that treats all non-zero whitespace the same (and different from zero whitespace), but what I want is for zero whitespace to be treated the same as non-zero whitespace when a comma is involved.Anyway, I decided that being able to do proper float comparisons is more desirable than using ellipsis markers, so I added (hidden)
testsetup/testcleanupblocks as in my earlier comment.bsipocz commentedon Dec 20, 2019
yes, thus I think ideally
NORMALIZE_WHITESPACEshould deal with this, or should at least work with other directives better.pllim commentedon Jun 23, 2020
I just hit this very same problem over at astropy/astropy#10511 . Glad I am not going crazy. I also resorted to manually setting numpy print options, which isn't pretty in the user example.