Import custom modules in nengo_gui

[Tioz]

I feel really silly but I can’t work out how to import my custom modules in Nengo GUI. When running my script from the terminal, from the tests folder, I usually do it as:

PYTHONPATH=… python main.py

My directory is organised as:

Project/
  library/
      file.py
  tests/
      main.py

And I import file.py into main.py as:

from library.file import *

I cannot work out how to do the same in Nengo GUI. I have tried adding

import sys
sys.path.append(‘…’)

to my script but to now avail.

[xchoo]

As a quick check, if you run nengo from the Project folder like so:

cd Project
nengo tests/main.py

Does that work?

[Tioz]

No, still the same ModuleNotFoundError .

[xchoo]

Okay. So I tested this setup and it seems to work:

Folder structure:

Project/
    lib/
        __init__.py
        funcs.py
    tests/
        main.py

The contents of funcs.py:

import numpy as np
def sin_func(t):
    return np.sin(t * np.pi * 3)

The contents of main.py

import sys
import nengo

sys.path.append("../lib")

from funcs import sin_func

with nengo.Network() as model:
    input_node = nengo.Node(sin_func)

I think you might have been missing the __init__.py file in the library folder. Without that file, python imports will not work.

[Tioz]

It still doesn’t seem to work in the GUI, even with the __init.py__ in there. It obviously works fine from the terminal or in my IDE but I just can’t seem to understand how to make it find the package in Nengo GUI.

[xchoo]

The working directory for the NengoGUI is the directory in which you initiated the nengo command. So, in your example, the working directory is the <root> directory. Python is thus trying to look for the memristor_nengo package in <root>/.., which doesn’t exist.

For your use case, if you start Nengo from the <root> directory, you’ll want to do:

sys.path.append("memristor_nengo")

You can also use absolute paths (instead of relative paths) in sys.path.append to get the import to work from any directory.

[Tioz]

Unfortunately, still no luck.
I’ve added the __init.py__ to the package, launched nengo from my root project folder, and tried to import with sys.path.append("memristor_nengo") from the main that is in root/tests.
I still get

Traceback (most recent call last):
File “/Users/thomastiotto/opt/anaconda3/envs/nengodl_opt/lib/python3.7/site-packages/nengo_gui/page.py”, line 229, in execute
exec(compiled, code_locals)
File “<nengo_gui_compiled>”, line 14, in
ModuleNotFoundError: No module named ‘memristor_nengo’

[xchoo]

Ah. I see your issue here. You are importing your modules as

from memristor_nengo.extras import *
from memristor_nengo.learning_rules import mPES

And this means that python is trying to find the memristor_nengo module from the directories in your path. Since you did sys.path.append("memristor_nengo"), it’s trying to find the memristor_nengo module (or folder) from within ./memristor_nengo, which it would not be able to find.

Therefore, if you use from memristor_nengo... import ..., you’ll want to do sys.path.append(".") instead.

Or, if you want to do sys.path.append("memristor_nengo"), you’ll have to do from extras import * and from learning_rules import mPES.

[Tioz]

It was so simple… It works now, thank you!