BUG: np.ma.asarray does not interrogate a foreign object for __array__. Should it? #29475
Description
Describe the issue:
This is how the masked and not-masked asarray treats a numpy array
In [1]: import numpy as np
In [2]: array = np.ma.array([1,2,3], mask=[False,True,False])
In [3]: np.asarray(array)
Out[3]: array([1, 2, 3])
In [4]: np.ma.asarray(array)
Out[4]:
masked_array(data=[1, --, 3],
mask=[False, True, False],
fill_value=999999)Now if I wrap my array object into a custom array class that implements __array__. np.asarray is fine with it but np.ma.asarray gives RecursionError: maximum recursion depth exceeded when you try to look at the array.
In [5]: class Array:
...: def __init__(self, data):
...: self._data = data
...: def __array__(self):
...: return self._data
...:
In [6]: x = Array(array)
In [7]: np.asarray(x)
Out[7]: array([1, 2, 3])
In [8]: np.ma.asarray(x)
Out[8]: ---------------------------------------------------------------------------
RecursionError Traceback (most recent call last)It appears that looking at the data is problematic
In [9]: out = np.ma.asarray(x)
In [10]: out.mask
Out[10]: array([False, True, False])
In [11]: out.data
Out[11]: ---------------------------------------------------------------------------
RecursionError Traceback (most recent call last)Now of course, if I use the __array__ method manually, np.ma.asarray is fine.
In [12]: np.ma.asarray(x.__array__())
Out[12]:
masked_array(data=[1, --, 3],
mask=[False, True, False],
fill_value=999999)Therefore, my bug report/question is should np.ma.asarray look for a __array__ to convert the object properly?
Reproduce the code example:
import numpy as np
array = np.ma.array([1,2,3], mask=[False,True,False])
class Array:
def __init__(self, data):
self._data = data
def __array__(self):
return self._data
x = Array(array)
print(np.asarray(x))
print(np.ma.asarray(x))Error message:
Traceback (most recent call last):
File "<python-input-0>", line 10, in <module>
print(np.ma.asarray(x))
~~~~~^^^^^^^^^^^^^^^^^^
File "/Users/iason/software/numpy/build-install/usr/lib/python3.13/site-packages/numpy/ma/core.py", line 4089, in __str__
return str(self._insert_masked_print())
File "/Users/iason/software/numpy/build-install/usr/lib/python3.13/site-packages/numpy/ma/core.py", line 4089, in __str__
return str(self._insert_masked_print())
File "/Users/iason/software/numpy/build-install/usr/lib/python3.13/site-packages/numpy/ma/core.py", line 4089, in __str__
return str(self._insert_masked_print())
[Previous line repeated 161 more times]
File "/Users/iason/software/numpy/build-install/usr/lib/python3.13/site-packages/numpy/ma/core.py", line 4068, in _insert_masked_print
data = self._data
^^^^^^^^^^
File "/Users/iason/software/numpy/build-install/usr/lib/python3.13/site-packages/numpy/ma/core.py", line 3787, in _get_data
return ndarray.view(self, self._baseclass)
~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^
RecursionError: maximum recursion depth exceededPython and NumPy Versions:
2.4.0.dev0+git20250728.f41d553
3.13.5 (tags/v3.13.5:6cb20a219a8, Jul 27 2025, 04:35:36) [Clang 17.0.0 (clang-1700.0.13.5)]
Runtime Environment:
[{'numpy_version': '2.4.0.dev0+git20250728.f41d553',
'python': '3.13.5 (tags/v3.13.5:6cb20a219a8, Jul 27 2025, 04:35:36) [Clang '
'17.0.0 (clang-1700.0.13.5)]',
'uname': uname_result(system='Darwin', node='coffeabox', release='24.5.0', version='Darwin Kernel Version 24.5.0: Tue Apr 22 19:53:27 PDT 2025; root:xnu-11417.121.6~2/RELEASE_ARM64_T6041', machine='arm64')},
{'simd_extensions': {'baseline': [], 'found': [], 'not_found': []}}]
Context for the issue:
Interoperability with NumPy when a foreign object is like a masked array (or can be converted into one).