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VS Code recognized the import but still shows ModuleNotFoundError

I am currently developing some packages with multiple subfolders. However, when I try to import one function from a subfolder into another one, the VS code shows green but when I run it, the terminal says ModuleNotFoundError. The folder structure is shown below.
Folder
|-Subfolder_1
|-- __init__.py
|-- fitting.py
|- Subfolder_2
|-- __init__.py
|-- process.py
|- main.py
When I import subfolder_1 to main.py, it works fine, but when I try to import fitting.py to process.py, the problem occurs. I tried to mess around with the settings in vscode but nothing worked. I also tried to just put them in the same subfolder, but when I do that, the process.py functions properly but main.py throws an error for modules not found since I use process.py in the main.py.
If anyone has some idea of how to fix it, it would be greatly appreciated.
EDIT 1:
Tried the sys.path.append for importing and the same error occurred.
Traceback (most recent call last):
File "path/to/file/subfolder_2/process.py", line 6, in <module>
import fitting
ModuleNotFoundError: No module named 'fitting'
EDIT 2: When I move fitting.py into the same subfolder with process.py and import fitting, the code runs and behave properly (folder structure after the traceback message). However, when I call functions in process.py in main.py by import, this error occurred:
Traceback (most recent call last):
File "/path/to/main.py", line 4, in <module>
from subfolder_1 import process
File "/path/to/subfolder_1/process.py", line 4, in <module>
import Fitting
ModuleNotFoundError: No module named 'Fitting'
Folder
|- Subfolder_1
|-- __init__.py
|-- process.py
|-- fitting.py
|- main.py
EDIT 3: I am currently working with a workaround for this by having fitting.py and process.py in the same subfolder but not calling process.py within main.py and have another file for the functions used for main.py; however, I would like to know why is this error occurring and what can fit it since it would be great for future reference if I have to revert back to the old structure.

If you are using virtual environment then you need activate it.
for Mac OS / Linux
source <path to env>/bin/activate
for Windows
<path to env>\Scripts\activate

You can try adding a path. However, it should be noted that vscode searches for files with the workspace as the root directory.
Here I assume that you have a workspace that contains your directory structure.
You can try:
import sys
sys.path.append(".\Folder\Subfolder_1")
import fitting
Example:
Here my_python is my workspace. And it involves a project named mainfloder like your **Floder**.
import sys
sys.path.append(".\mainfloder\projectfloder\pages")
from webpages import SignUpPage
print(SignUpPage())
I can get it.

Python3.6 ImportError when running script outside the directory. Runs correctly within same directory

I have the following set up.
~/python/pyct/lib/
├── printer.py
└── utils.py
~/apps/proj/
└── main.py
~/python/pyct/lib/utils.py
def printFunc(content):
print(content)
~/python/pyct/lib/printer.py
import utils # this breaks sometimes
# import pyct.lib.utils as utils # this works always
def printer(content):
utils.printFunc(content)
~/apps/proj/main.py
from pyct.lib.printer import printer
printer("hi")
Value of PYTHONPATH=$HOME/python
When I import printer.py in a file inside ~/python/pyct/lib/, everything runs as expected.
When I run main.py from ~/apps/proj/, I get the following error:
Traceback (most recent call last):
File "main.py", line 1, in <module>
from pyct.lib.printer import printer
File "~/python/pyct/lib/printer.py", line 1, in <module>
import utils
ModuleNotFoundError: No module named 'utils'
I have tried using relative imports but that doesn't work. I have gone through this resource but could get the scenario working.
I am aware that the problem can be solved using absolute path in imports but I want to make a dir with multiple python files which will act as a library. Then use the core component else where outside the directory.
How can I achive the above scenario working.
Any resources to understand python imports will be very helpful.

The problem here is that ~/python/pyct/lib/printer.py looks for module named utils in its working directory - not in directory where it is placed itself.
You can use relative import in ~/python/pyct/lib/printer.py:
from . import utils
python will then look for module relative to the path of the importing one instead of working directory.

Project structure, how to create subpackage that will work independently?

Python 3.6+, directory structure:
project/
main.py
subpackage/
submain.py
config.py
main.py:
from subpackage.submain import attribute1
if __name__ == "__main__":
print(attribute1)
submain.py:
from config import config_param
attribute1 = 1 + config_param
config.py:
config_param = 100
it throws error:
Traceback (most recent call last):
File "/projects/test/project/main.py", line 1, in <module>
from subpackage.subname import attribute1
File "/projects/test/project/subpackage/subname.py", line 1, in <module>
from config import config_param
ModuleNotFoundError: No module named 'config'
We use couple gitsubmodule in our project and for now it works with:
from .config import config_param
But I am sure that this is wrong solution because it is already require in some folder/folder/folder to create such relative import ...config or ../../../config.
I already spent a week to find how to do this so that subpackage could work independently(from config import config_param), any help, links appreciate, thanks

try to add __init__.py files in your dirs https://docs.python.org/3/tutorial/modules.html

One solution that should work :
Add __init__.py in the subpackage,
Add the subpackage directory in PYTHONPATH, you can also do it with :
sys.path.append(PATH_TO_THE_SUBPACKAGE) .
The package is now part of the PYTHONPATH, so you can import it like any other libraries with import config.

cannot find module in another directory

I have the project structure:
/hdfs-archiver
/logs
/qe
__init__.py
/tests
__init__.py
archiver.py
/utils
__init__.py
HdfsConnector.py
I am trying to run archiver.py but I am getting this error:
Traceback (most recent call last):
File "qe/tests/HdfsArchiver.py", line 8, in <module>
from qe.utils import HdfsConnector
ImportError: No module named qe.utils
I read around and it seemed like most people that come across this issue fixed it with __init__.py
when I pwd:
$ pwd
/Users/bli1/Development/QE/idea/hdfs-archiver
my PYTHONPATH in .bashrc
export PYTHONPATH=$PYTHONPATH:/Users/bli1/Development/QE/idea/hdfs-archiver
I also tried having my PYTHONPATH as
/Users/bli1/Development/QE/idea/hdfs-archiver/qe

You're trying to import HdfsConnector as a function or class. Include the HdfsConnector module as part of your absolute import:
from qe.utils.HdfsConnector import my_function
You can also import the module:
import qe.utils.HdfsConnector
# or
import qe.utils.HdfsConnector as HdfsConnector

Firstly, you could try a relative import such as
from ..utils import HdfsConnector
You'd also need to run the script as a module and not as a simple python script due to the __name__ being different. This wouldn't require you to modify the path.
You can find more info here.

Python imports with __init__.py

No matter how I structure the imports in the code files and in the __init__.py files, I can't seem to get it right for executing the program and running the tests using pytest. How do I need to write the imports when my project structure looks like this:
src/
__init__.py
VocableFileWriter.py
WordListHelper.py
WordListReader.py
XLDAttributeValueAdder.py
exceptions/
__init__.py
XMLInvalidException.py
XMLParseException.py
gui/
__init__.py
GTKSignal.py
XLDAttributeValueAdderWindow.py
test/
__init__.py
test_XLDAttributeValueAdder.py
xmlparser/
__init__.py
XMLParser.py
Currently I have them like this:
In the __init__.py files I have the imports like this (src/__init__.py):
from src import *
from src.exceptions import *
from src.xmlparser import *
and in a subpackage (src/xmlparser/__init__.py):
from src.xmlparser import *
So I guess those are project-absolute paths to the modules.
In the code files themselves I import like this:
import os
import sys
from VocableFileWriter import VocableFileWriter
from XLDAttributeValueAdder import XLDAttributeValueAdder
However, when I execute the code from the directory above src using:
./src/main.py
It tells me that:
Traceback (most recent call last):
File "./src/main.py", line 6, in <module>
from VocableFileWriter import VocableFileWriter
File "/home/xiaolong/Development/PycharmProjects/xld-attribute-value-adder/src/VocableFileWriter.py", line 2, in <module>
from XMLInvalidException import XMLInvalidException
ImportError: No module named 'XMLInvalidException'
It used to be a PyCharm project, but I couldn't get it to run with the imports structure PyCharm used when not using PyCharm but running it from the terminal, so I decided I wanted to take the whole import stuff into my own hands. So don't get confused by it being in a PyCharm directory.
I also want to be able to execute the tests using for example:
py.test src/test/test_XLDAttributeValueAdder.py
How do I solve this mess?
Edit#1:
I had the program running once, but then the test complained about missing modules, probably because it's in another subdirectory and I tried so many configurations, that I don't know how I had the program running anymore. If possible please add some explanation why a certain structure is correct and works for both, tests and the program itself.
EDIT#2:
I've managed to get the tests running now, but now the program doesn't run anymore.
I emptied all the __init__.py files and used only project-absolute paths in the code files like this (src/test/test_XLDAttributeValueAdder.py):
from src.VocableFileWriter import VocableFileWriter
from src.WordListHelper import WordListHelper
from src.WordListReader import WordListReader
from src.XLDAttributeValueAdder import XLDAttributeValueAdder
from src.exceptions.XMLInvalidException import XMLInvalidException
from src.exceptions.XMLParseException import XMLParserException
from src.xmlparser.XMLParser import XMLParser
from src.test.path_helper import go_up
from src.test.path_helper import go_in
and in the main.py:
from src.VocableFileWriter import VocableFileWriter
from src.XLDAttributeValueAdder import XLDAttributeValueAdder
the output of ./src/main.py:
./src/main.py
Traceback (most recent call last):
File "./src/main.py", line 6, in <module>
from src.VocableFileWriter import VocableFileWriter
ImportError: No module named 'src'
EDIT#3:
I've tried the relative import way like this:
main.py moved one directory up
The structure now looks like this:
main.py
src/
__init__.py
VocableFileWriter.py
WordListHelper.py
WordListReader.py
XLDAttributeValueAdder.py
exceptions/
__init__.py
XMLInvalidException.py
XMLParseException.py
gui/
__init__.py
GTKSignal.py
XLDAttributeValueAdderWindow.py
test/
__init__.py
test_XLDAttributeValueAdder.py
xmlparser/
__init__.py
XMLParser.py
__init__.py files empty
main.py file gets relative
Imports look like this:
import os
import sys
from .src.VocableFileWriter import VocableFileWriter
from .src.XLDAttributeValueAdder import XLDAttributeValueAdder
When I try to run the main.py file:
Traceback (most recent call last):
File "main.py", line 6, in <module>
from .src.VocableFileWriter import VocableFileWriter
SystemError: Parent module '' not loaded, cannot perform relative import
However, there is a __init__.py file in the same directory as the main.py file, also empty.

You'd better use relative imports.
When doing from src import * in src/__init__.py you'll only import anything you've defined before calling the import. Most likely that's just nothing. If you've defined the __all__ variable, you'll get the submodule from it, but maybe also an AttributeError if a variable hasn't been defined yet.
So instead import the modules you need explicitly where you need them like
from .VocableFileWriter import VocableFileWriter
from .exceptions.XMLInvalidException import XMLInvalidException
or lets say within src/gui/GTKSignal.py
from ..exceptions.XMLInvalidException import XMLInvalidException
Also you could use project-absolute paths like mentioned in your Edit#2.
Furthermore you've a problem with your path when calling ./src/main.py. In this case the directory containing src is not in the path. Instead ./src/ is in the path. Therefore python doesn't consider it a package anymore and since there's no other package with that name available, the import fails.
Instead put your main.py module in the same directory like the src package or call it as a module with python -m src.main. Doing so you could also rename it to src/main.py and call the package instad with python -m src.
When using the first approach, main should use an absolute import structure. Just think of it as a module you put anywhere on your computer, while your src package is somewhere else, where it can be found by Python, like any other module or package installed by the system. It's not different, when it's located besides the package itself, since the current directory is in sys.path.
main.py
import os
import sys
from src.VocableFileWriter import VocableFileWriter
from src.XLDAttributeValueAdder import XLDAttributeValueAdder