Handle numpy missing the array api function astype

[Illviljan]

This is how our get_array_namespace works:

xarray/xarray/core/duck_array_ops.py

Lines 44 to 48 in dafd726

	def get_array_namespace(x):
	if hasattr(x, "__array_namespace__"):
	return x.__array_namespace__()
	else:
	return np

Which usually works. But not for astype.

Using np.array_api doesn't work because you have to use np.array_api.Array instead of np.ndarray:

import numpy.array_api as nxp
nxp.astype(np.array([1, 2,]), np.dtype(float))

Traceback (most recent call last):

  File "C:\Users\J.W\AppData\Local\Temp\ipykernel_8616\23329947.py", line 1, in <cell line: 1>
    nxp.astype(np.array([1, 2,]), np.dtype(float))

  File "C:\Users\J.W\anaconda3\envs\xarray-tests\lib\site-packages\numpy\array_api\_data_type_functions.py", line 20, in astype
    return Array._new(x._array.astype(dtype=dtype, copy=copy))

AttributeError: 'numpy.ndarray' object has no attribute '_array'

I found it simpler to just change astype here.

An alternative solution would be to use: https://github.com/data-apis/array-api-compat
cubed-dev/cubed#317

Seen in #8294.

[dcherian]

The namespace for numpy is numpy.array_api and np.array_api.astype exists. It seems like this should just work.

[Illviljan]

This is how our get_array_namespace works:

xarray/xarray/core/duck_array_ops.py

Lines 44 to 48 in dafd726

	def get_array_namespace(x):
	if hasattr(x, "__array_namespace__"):
	return x.__array_namespace__()
	else:
	return np

Which usually works. But not for astype.

Using np.array_api doesn't work because you have to use np.array_api.Array instead of np.ndarray:

import numpy.array_api as nxp
nxp.astype(np.array([1, 2,]), np.dtype(float))

Traceback (most recent call last):

  File "C:\Users\J.W\AppData\Local\Temp\ipykernel_8616\23329947.py", line 1, in <cell line: 1>
    nxp.astype(np.array([1, 2,]), np.dtype(float))

  File "C:\Users\J.W\anaconda3\envs\xarray-tests\lib\site-packages\numpy\array_api\_data_type_functions.py", line 20, in astype
    return Array._new(x._array.astype(dtype=dtype, copy=copy))

AttributeError: 'numpy.ndarray' object has no attribute '_array'

I found it simpler to just change astype here.

[dcherian]

I found it simpler to just change astype here.

Great, thanks for the explanation!