Why can py.numpy.array not be resolved?

Hello,

I am trying run python from within Matlab. Unfortunately, I I even fail to use numpy (see below). I would very much appreciate any suggestions as to why that could be. I am using Matlab 2019b on Winows 10.

>> pyversion

       version: '3.7'
    executable: 'C:\Users\wolf5212\AppData\Local\Programs\Python\Python37\python.exe'
       library: 'C:\Users\wolf5212\AppData\Local\Programs\Python\Python37\python37.dll'
          home: 'C:\Users\wolf5212\AppData\Local\Programs\Python\Python37'
      isloaded: 0

>> py.str(1)

ans = 

  Python str with no properties.

    1.0

>> py.numpy.array([])
Unable to resolve the name py.numpy.array.

Importing numpy from the command prompt is no problem.

H:\>python
Python 3.7.6 (tags/v3.7.6:43364a7ae0, Dec 19 2019, 01:54:44) [MSC v.1916 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import numpy
>>> exit()

Answer 1

[Igor Varfolomeev]

I ran into a similar issue recently, but I'm not sure it it's 100% same.

What I can suggest is:

1. Try CPython 3.6.8 ( https://www.python.org/downloads/release/python-368/ ) first.

2. Try "InProcess" mode:

pe=pyenv('Version','C:\path\to\Python36\pythonw.exe',...
         ...'ExecutionMode','OutOfProcess'...  --- this (new mode) causes misc. issues in R2019b update 5
         'ExecutionMode','InProcess'...  --- this (old mode) works OK
         );  

3. Try to explicitly import numpy:

pe=pyenv('Version','C:\path\to\Python36\pythonw.exe',...         
         'ExecutionMode','InProcess');  
py.importlib.import_module('numpy')

if it produces something like this:

>> py.importlib.import_module('numpy')
Error using __init__><module> (line 54)
Python Error: ImportError:

IMPORTANT: PLEASE READ THIS FOR ADVICE ON HOW TO SOLVE THIS ISSUE!

Importing the numpy c-extensions failed.
- Try uninstalling and reinstalling numpy.
<...>

it is likely that Python cannot see the necessary dll files. Adding them to path fixes the issue for me.

This only happens to me when I use Anaconda python installation :

conda create -n test_py36 python=3.6 numpy

I never ran into this issue when using CPython 3.6.8.

But for Anaconda, the issue could be fixed by simply adding the folder with the neccessary dlls to %PATH%:

username = getenv('username');
setenv('PYTHONUNBUFFERED','1'); % doesn't change much, but just-in-case
setenv('path',['C:\Users\' username '\Anaconda3\envs\test_py36\Library\bin;', getenv('path')]);
                       
pe=pyenv('Version',['C:\Users\' username '\Anaconda3\envs\test_py36\pythonw.exe'],...         
         'ExecutionMode','InProcess');
     
py.importlib.import_module('numpy')

[Paul F Lang]

Thanks a lot Igor, I'll try that out next time I'll get back to this problem.

[Gustavo Pacheco]

Thanks