pytorch

d168eae1 - make torch.testing error messages more expressive (#55145)

make torch.testing error messages more expressive (#55145) Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/55145 Repeating the discussion from https://github.com/pytorch/pytorch/pull/54784#issuecomment-811792089 The error messages for mismatched values are directly adapted from the old `_compare_tensors_internal`: https://github.com/pytorch/pytorch/blob/50cb75edcef41b82fefe957f95b470dfffe53710/torch/testing/__init__.py#L104-L111 A sample error message right now looks like this ``` With rtol=1.3e-06 and atol=1e-05, found 1 different element(s) out of 12 (8.3%). The greatest difference of 4.0 (5.0 vs. 9.0) occurred at index (2, 3) ``` Using the same data with `numpy.testing.assert_equal` gives the following output: ``` Not equal to tolerance rtol=1.3e-06, atol=1e-05 Mismatched elements: 1 / 12 (8.33%) Max absolute difference: 4. Max relative difference: 0.44444445 x: array([[5., 5., 5., 5.], [5., 5., 5., 5.], [5., 5., 5., 5.]], dtype=float32) y: array([[5., 5., 5., 5.], [5., 5., 5., 5.], [5., 5., 5., 9.]], dtype=float32) ``` Pros: - The info is presented in a list instead of a sentence. IMO this makes it more readable - The maximum relative difference is reported, which is beneficial in case a comparison fails due to the `rtol` Cons: - The values of the inputs are reported (this can be disabled by passing `verbose=False`, but lets face it: most users will use the default setting). In case the inputs are large, the output gets truncated with `...`. Not only is it hard to visually find the mismatching values, they could also live within the truncated part, making the output completely useless. - Even when visually find the offending values it is hard to parse this back to the index in the inputs. This implements a mix of both to get a short but expressive message: ``` Tensors are not close according to rtol=1.3e-6 and atol=1e-05: Mismatched elements: 1 / 12 (8.3%) Max. rel. diff.: 4.44e-1 at (2, 3) Max. abs. diff.: 4.0 at (2, 3) ``` Test Plan: Imported from OSS Reviewed By: heitorschueroff Differential Revision: D27877157 Pulled By: mruberry fbshipit-source-id: 6898a995f116f127e3ae8ed0bcb1ada63eadc45a