Incompatibility of Python3.8+, Cython, Numpy, and Numba

[yangyushi]

Some user with Python version newer than 3.8 might experience following issue when importing nplocate.

>>> import nplocate
Traceback (most recent call last):
 File “<stdin>“, line 1, in <module>
 File “.../python3.8/site-packages/nplocate/__init__.py”, line 4, in <module>
  from .model import GaussianSphere
 File “.../python3.8/site-packages/nplocate/model.py”, line 16, in <module>
  from nplocate import csimulate
 File “nplocate/csimulate.pyx”, line 1, in init nplocate.csimulate
ValueError: numpy.ndarray size changed, may indicate binary incompatibility. Expected 96 from C header, got 88 from PyObject

After some experiment I think this is related to the version of numpy (1.20.x). It needs to be upgraded to 1.22.x, so that the Cython compiled code csimulate.pyx could work.

So, if you see the error, try to upgrade the numpy to latest version.

However, the situation can be harder when numba is taken into consideration. The current numba version (0.54.1) does not support numpy 1.21.x +. Hopefully the numba people will support latest numpy at some point. At the moment, the way to solve the issue seems to be using an older Python (like Python 3.7).