add apply_over_axes API

[syheliel]

Hello, the community! This PR is to contribute a little step forward #6078. It's my first time to get involved in cupy :)

implement Code is from: https://github.com/numpy/numpy/blob/8f7e4c57931569760a036599ade6955ecc387c84/numpy/lib/_shape_base_impl.py#L413

Test code is from: https://github.com/numpy/numpy/blob/8f7e4c57931569760a036599ade6955ecc387c84/numpy/lib/tests/test_shape_base.py#L274

[asi1024]

Could you add another test for axes.ndim == 0 for coverage?

[syheliel]

add test_apply_over_axis_invalid_0darr

[asi1024]

Could you add another test for res.ndim == val.ndim?

[asi1024]

Could you add this test?

[syheliel]

Yes, I'm working on it.

[syheliel]

add test_apply_over_axis_shape_preserve_func

[asi1024]

This line should not raise AttributeError.

[syheliel]

I've Changed it into numpy.AxisError

[syheliel]

I found that cupy behaves different from numpy in 0-demension array.

cupy will throw an AxisError:

import cupy as cp
a = cp.array(42)
cp.apply_over_axes(cp.sum, a, 0) 
# error msg:
  File "<stdin>", line 1, in <module>
  File "/home/xxx/cupy/cupy/lib/_shape_base.py", line 136, in apply_over_axes
    axis = internal._normalize_axis_index(axis, N)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "cupy/_core/internal.pyx", line 417, in cupy._core.internal._normalize_axis_index
    cpdef Py_ssize_t _normalize_axis_index(
  File "cupy/_core/internal.pyx", line 437, in cupy._core.internal._normalize_axis_index
    raise numpy.AxisError(axis, ndim)
numpy.exceptions.AxisError: axis 0 is out of bounds for array of dimension 0

But numpy will not throw an error:

import numpy as np
a = np.array(42)
np.apply_over_axes(cp.sum, a, 0)  # returns [42]

The key difference is that cupy uses:

axis = internal._normalize_axis_index(axis, N)

but numpy uses

        if axis < 0:
            axis = N + axis

I will make the behavior the same with numpy. But also add a comment on there.

[syheliel]

HI, I have fixed all the problems. Would you like to take a look?

[asi1024]

@syheliel Could you fix for CI failures?

[mergify]

This pull request is now in conflicts. Could you fix it @syheliel? 🙏

[syheliel]

got it， I will fix it later

[asi1024]

CIs are still failing. We can provide assistance if needed. 😃

[syheliel]

@asi1024 thanks! I have located where is the problem and I'm trying to fix/test it on my local machine

[syheliel]

I've fixed the flake8 problem. But I can't find a way to fix this in doc:

/home/runner/work/cupy/cupy/docs/source/reference/functional.rst:13: WARNING: autosummary: failed to import apply_over_axis.
Possible hints:
* ValueError: not enough values to unpack (expected 2, got 1)
* ModuleNotFoundError: No module named 'apply_over_axis'
* ModuleNotFoundError: No module named 'cupy.apply_over_axis'
* KeyError: 'apply_over_axis'
* AttributeError: module 'cupy' has no attribute 'apply_over_axis'
looking for now-outdated files... none found
pickling environment... done
checking consistency... done

Would you like take a look?

[asi1024]

Suggested change

	apply_over_axis
	apply_over_axes