[Numpy-discussion] Adding "maximum difference" to np.testing.assert_array_equal errors

[Christoph Deil]

> On 19. Dec 2018, at 19:50, Stefan van der Walt <stefanv at berkeley.edu> wrote:
> 
> On Wed, 19 Dec 2018 09:47:01 -0800, Stephan Hoyer wrote:
>> Example behavior:
>> 
>>>>> x = np.array([1, 2, 3])
>>>>> y = np.array([1, 2, 3.0001])
>>>>> np.testing.assert_allclose(x, y)
>> AssertionError:
>> Not equal to tolerance rtol=1e-07, atol=0
>> 
>> (mismatch 33.333333333333336%, maximum difference
>> 0.00010000000000021103)
> 
> This is a helpful addition; thank you!  I don't have a strong preference
> around whether to also include rtol.
> 
> Stéfan
> _______________________________________________
> NumPy-Discussion mailing list
> NumPy-Discussion at python.org
> https://mail.python.org/mailman/listinfo/numpy-discussion

+1 to this addition.

And +1 to also print rtol.
I frequently use rtol with assert_allclose, and having the value printed helps quickly choose an appropriate value.

Christoph