Type of return value from indexing

[shoyer]

The current spec is silent on what the return value from an indexing operation should be: https://data-apis.github.io/array-api/latest/API_specification/indexing.html

I propose that the return value should always be another array object, i.e., so __getitem__ could be type annotated as __getitem__(self: Array, key: IndexKey) -> Array. However, this is inconsistent with NumPy, which returns NumPy scalars in some cases when indexing with integers.

[rgommers]

Thanks @shoyer. I agree with that proposal. This is what most libraries do I think - PyTorch, JAX, TensorFlow, Dask and MXNet (from memory, will verify later), with only CuPy agreeing (?) with NumPy here.

[leofang]

CuPy always returns array too.

[rgommers]

Thanks Leo. I didn't have a GPU machine at hand and couldn't find it in the docs. Turns out it's documented after all: https://docs.cupy.dev/en/stable/reference/difference.html#zero-dimensional-array

[rgommers]

This was fixed in gh-125, closing.