Develop Reference

How to mark src folder as Sources Root through linux terminal?

I am trying to run a python file from terminal. It has a bunch of imports from modules I wrote, and those modules also import from other modules from throughout my project. As PyCharm was my main editor, I could mark the src directory as Sources Root, which allowed me to import other modules in two ways. Say I have a module shared, I could import from it as:
from src.shared.timer import Timer
But also as:
from shared.timer import Timer
When I run my script main.py from within pycharm everything runs perfectly
The problem is that when I run main.py from command line, my imports give error "No module named shared" or "No module named src" depending on whether I call from the top-level directory or from the src directory. Either way, I can never get all imports right. Is there a way to mark my src directory as Sources Root, similar to in PyCharm? I want to avoid refactoring everything and then finding out there is some other issue.
from top level directory in repository, I tried to run
python3.8 -m src.main.py
and got
ModuleNotFoundError: No module named 'shared'

Unable to import from __init__.py [duplicate]

I'm having a hard time understanding how module importing works in Python (I've never done it in any other language before either).
Let's say I have:
myapp/__init__.py
myapp/myapp/myapp.py
myapp/myapp/SomeObject.py
myapp/tests/TestCase.py
Now I'm trying to get something like this:
myapp.py
===================
from myapp import SomeObject
# stuff ...
TestCase.py
===================
from myapp import SomeObject
# some tests on SomeObject
However, I'm definitely doing something wrong as Python can't see that myapp is a module:
ImportError: No module named myapp

In your particular case it looks like you're trying to import SomeObject from the myapp.py and TestCase.py scripts. From myapp.py, do
import SomeObject
since it is in the same folder. For TestCase.py, do
from ..myapp import SomeObject
However, this will work only if you are importing TestCase from the package. If you want to directly run python TestCase.py, you would have to mess with your path. This can be done within Python:
import sys
sys.path.append("..")
from myapp import SomeObject
though that is generally not recommended.
In general, if you want other people to use your Python package, you should use distutils to create a setup script. That way, anyone can install your package easily using a command like python setup.py install and it will be available everywhere on their machine. If you're serious about the package, you could even add it to the Python Package Index, PyPI.

The function import looks for files into your PYTHONPATH env. variable and your local directory. So you can either put all your files in the same directory, or export the path typing into a terminal::
export PYTHONPATH="$PYTHONPATH:/path_to_myapp/myapp/myapp/"

exporting path is a good way. Another way is to add a .pth to your site-packages location.
On my mac my python keeps site-packages in /Library/Python shown below
/Library/Python/2.7/site-packages
I created a file called awesome.pth at /Library/Python/2.7/site-packages/awesome.pth and in the file put the following path that references my awesome modules
/opt/awesome/custom_python_modules

You can try
from myapp.myapp import SomeObject
because your project name is the same as the myapp.py which makes it search the project document first

You need to have
__init__.py
in all the folders that have code you need to interact with.
You also need to specify the top folder name of your project in every import even if the file you tried to import is at the same level.

In your first myapp directory ,u can add a setup.py file and add two python code in setup.py
from setuptools import setup
setup(name='myapp')
in your first myapp directory in commandline , use pip install -e . to install the package

pip install on Windows 10 defaults to installing in 'Program Files/PythonXX/Lib/site-packages' which is a directory that requires administrative privileges. So I fixed my issue by running pip install as Administrator (you have to open command prompt as administrator even if you are logged in with an admin account). Also, it is safer to call pip from python.
e.g.
python -m pip install <package-name>
instead of
pip install <package-name>

In my case it was Windows vs Python surprise, despite Windows filenames are not case sensitive, Python import is. So if you have Stuff.py file you need to import this name as-is.

let's say i write a module
import os
my_home_dir=os.environ['HOME'] // in windows 'HOMEPATH'
file_abs_path=os.path.join(my_home_dir,"my_module.py")
with open(file_abs_path,"w") as f:
f.write("print('I am loaded successfully')")
import importlib
importlib.util.find_spec('my_module') ==> cannot find
we have to tell python where to look for the module. we have to add our path to the sys.path
import sys
sys.path.append(file_abs_path)
now importlib.util.find_spec('my_module') returns:
ModuleSpec(name='my_module', loader=<_frozen_importlib_external.SourceFileLoader object at 0x7fa40143e8e0>, origin='/Users/name/my_module.py')
we created our module, we informed python its path, now we should be able to import it
import my_module
//I am loaded successfully

This worked for me:
from .myapp import SomeObject
The . signifies that it will search any local modules from the parent module.

Short Answer:
python -m ParentPackage.Submodule
Executing the required file via module flag worked for me. Lets say we got a typical directory structure as below:
my_project:
| Core
->myScript.py
| Utils
->helpers.py
configs.py
Now if you want to run a file inside a directory, that has imports from other modules, all you need to do is like below:
python -m Core.myscript
PS: You gotta use dot notation to refer the submodules(Files/scripts you want to execute). Also I used python3.9+. So I didnt require neither any init.py nor any sys path append statements.
Hope that helps! Happy Coding!

If you use Anaconda you can do:
conda develop /Path/To/Your/Modules
from the Shell and it will write your path into a conda.pth file into the standard directory for 3rd party modules (site-packages in my case).

If you are using the IPython Console, make sure your IDE (e.g., spyder) is pointing to the right working directory (i.e., your project folder)

Besides the suggested solutions like the accepted answer, I had the same problem in Pycharm, and I didn't want to modify imports like the relative addressing suggested above.
I finally found out that if I mark my src/ (root directory of my python codes) as the source in Interpreter settings, the issue will be resolved.

Python module import - why is it not working?

I'm trying to install LLDB-3.5 on my system, and I'm having incredibly difficult time getting the python2.7 binding modules to load.
The module has the usual structure
/ LLDB
+ __init__.py
+ some_file.py
+ _lldb.so
/ subdirectory
I've verified that path to the module is in PYTHONPATH. I've checked the results of sys.path, its there, and I can directly import some_file.py
import some_file # This line compiles happily.
Weirdly, I can also import init.py
import __init__ # This line complains its missing module lldb.some_file
I did have lldb-3.4 installed, but if I add a print statement in that file, it displays, so I'm definitely looking at this file.
However, when I try to import lldb, I get back
import lldb # ImportError: No module named lldb
I don't understand that.
It's a swig'ed Python wrapper to LLDB, but I've verified that the .so loads. calling "ldd _lldb.so" on the command line shows a good list of resolved dependencies. If I run the commands in init.py in the python shell, (ie, the calls to imp.find_module & imp.load_module) then the so file is loaded happily.
I'm sure this is a very basic issue, but I'm don't use Python much. I've do have virtualenv installed with Python 2.6, but I have of course verified I'm in the right version of Python.

Is the lldb directory itself on the path? For a package, you should have its containing directory (the parent directory of lldb) on sys.path.
(Normally I would expect the package installation to do this for you. However, the note at the very end of this page suggests that they're targeting the use case where you use the Python lldb module from within the lldb command-line program. So you have to set up the path manually.)

why i cannot invoke python script which is in the same project? [duplicate]

What is the correct way to fix this ImportError error?
I have the following directory structure:
/home/bodacydo
/home/bodacydo/work
/home/bodacydo/work/project
/home/bodacydo/work/project/programs
/home/bodacydo/work/project/foo
And I am in the directory
/home/bodacydo/work/project
Now if I type
python ./programs/my_python_program.py
I instantly get
ImportError: No module named foo.tasks
The ./programs/my_python_program.py contains the following line:
from foo.tasks import my_function
I can't understand why python won't find ./foo/tasks.py - it's there.
If I do it from the Python shell, then it works:
python
>>> from foo.tasks import my_function
It only doesn't work if I call it via python ./programs/my_python_program.py script.

Python does not add the current directory to sys.path, but rather the directory that the script is in. Add /home/bodacydo/work/project to either sys.path or $PYTHONPATH.

Do you have a file called __init__.py in the foo directory? If not then python won't recognise foo as a python package.
See the section on packages in the python tutorial for more information.

A better fix than setting PYTHONPATH is to use python -m module.path
This will correctly set sys.path[0] and is a more reliable way to execute modules.
I have a quick writeup about this problem, as other answerers have mentioned the reason for this is python path/to/file.py puts path/to on the beginning of the PYTHONPATH (sys.path).

Here is a step-by-step solution:
Add a script called run.py in /home/bodacydo/work/project and edit it like this:
import programs.my_python_program
programs.my_python_program.main()
(replace main() with your equivalent method in my_python_program.)
Go to /home/bodacydo/work/project
Run run.py
Explanation:
Since python appends to PYTHONPATH the path of the script from which it runs, running run.py will append /home/bodacydo/work/project. And voilà, import foo.tasks will be found.

Example solution for adding the library to your PYTHONPATH.
Add the following line into your ~/.bashrc or just run it directly:
export PYTHONPATH="$PYTHONPATH:$HOME/.python"
Then link your required library into your ~/.python folder, e.g.
ln -s /home/user/work/project/foo ~/.python/

In my mind I have to consider that the foo folder is a stand-alone library. I might want to consider moving it to the Lib\site-packages folder within a python installation. I might want to consider adding a foo.pth file there.
I know it's a library since the ./programs/my_python_program.py contains the following line:
from foo.tasks import my_function
So it doesn't matter that ./programs is a sibling folder to ./foo. It's the fact that my_python_program.py is run as a script like this:
python ./programs/my_python_program.py

If you have this problem when using an instaled version, when using setup.py, make sure your module is included inside packages
setup(name='Your program',
version='0.7.0',
description='Your desccription',
packages=['foo', 'foo.bar'], # add `foo.bar` here

Import python package from local directory into interpreter

I'm developing/testing a package in my local directory. I want to import it in the interpreter (v2.5), but sys.path does not include the current directory. Right now I type in sys.path.insert(0,'.'). Is there a better way?
Also,
from . import mypackage
fails with this error:
ValueError: Attempted relative import in non-package

You can use relative imports only from in a module that was in turn imported as part of a package -- your script or interactive interpreter wasn't, so of course from . import (which means "import from the same package I got imported from") doesn't work. import mypackage will be fine once you ensure the parent directory of mypackage is in sys.path (how you managed to get your current directory away from sys.path I don't know -- do you have something strange in site.py, or...?)
To get your current directory back into sys.path there is in fact no better way than putting it there.

Keep it simple:
try:
from . import mymodule # "myapp" case
except:
import mymodule # "__main__" case

See the documentation for sys.path:
http://docs.python.org/library/sys.html#sys.path
To quote:
If the script directory is not available (e.g. if the interpreter is invoked interactively or if the script is read from standard input), path[0] is the empty string, which directs Python to search modules in the current directory first.
So, there's no need to monkey with sys.path if you're starting the python interpreter from the directory containing your module.
Also, to import your package, just do:
import mypackage
Since the directory containing the package is already in sys.path, it should work fine.

If you want to run an unmodified python script so it imports libraries from a specific local directory you can set the PYTHONPATH environment variable - e.g. in bash:
export PYTHONPATH=/home/user/my_libs
python myscript.py
If you just want it to import from the current working directory use the . notation:
export PYTHONPATH=.
python myscript.py

Inside a package if there is setup.py, then better to install it
pip install -e .

A simple way to make it work is to run your script from the parent directory using python's -m flag, e.g. python -m packagename.scriptname. Obviously in this situation you need an __init__.py file to turn your directory into a package.

Using sys.path should include current directory already.
Try:
import .
or:
from . import sth
however it may be not a good practice, so why not just use:
import mypackage

A bit late to the party, but this is what worked for me:
>>> import sys
>>> sys.path.insert(0, '')
Apparently, if there is an empty string, Python knows that it should look in the current directory. I did not have the empty string in sys.path, which caused this error.

Speaking for python3.. I wanted to use an improved version of a library that's installed in my environment. There are some extra print statements it makes to show that it and not the original lib is being used.
I placed the lib's folder next to the python script. Ran the script.. it ran with the local lib with the modifications.
Removed the folder and ran it again - this time it ran with the installed lib.
So, solution was simple : place the lib's folder (with same name as in your import statement) in your project folder. That does the job, at least at my end.
This is on a standard Linux Mint 20.04 system, with a python 3.8 virutal environment activated (so "(py3.8)" appears in my terminal when I'm in the virtual env)

You can import package_name if the package is a module: this needs you have init.py under the package and things that you want to use are needed to import in the init.py
Or if you want to import class under the package, you can use from package_name import class_name