I'm creating a python 3.9 program and want to install packages locally. So the way my project is set up is this:
__main__.py
test.py
requirements.txt
lib/
__init__.py
In my requirements.txt file I have 3 lines:
colorama==0.2.2
click==8.0.3
pendulum==2.1.2
Then I run: python -m pip install -r requirements.txt -t ./lib
This installs all the packages and dependencies inside of the lib directory.
Then I import the modules at the top of my test.py file:
from lib import colorama
from lib import click
from lib import pendulum
In doing some testing, I've found that colorama works fine. I'll use it in a simple test:
print(colorama.Fore.BLUE + "Hello, World!"). The text is blue in the console and everything is working.
I then try to use the other packages and I get ModuleNotFoundError exception:
print(pendulum.now('Europe/Paris'))
Exception has occurred: ModuleNotFoundError - No module named 'pendulum'
This is coming from one of its own files.
The same thing happens when I use Click, but it's a little different. I'll get the same ModuleNotFound exception, but it's for its own dependency on Colorama. I don't think it's related to the fact that I'm also importing Colorama because if I uninstall I get the same error.
I've also tried this with the python-docx package. I added python-docx==0.8.11 to the requirements.txt file, then issued the same command as above to install to my local lib directory. It seems to install fine. I see the docx directory and all its dependencies. Then I import from lib import docx then do something simple in test.py:
doc = docx.Document()
Then get ModuleNotFound error: File "C:\Users\name\Development\python\test-local-package\lib\docx_init_.py", line 3, in (Current frame) No Module named 'docx'
Does anyone know what I'm doing wrong?
When you put those libraries into your lib folder and import them the way you are doing, you're changing their package names. No longer is colorama a top-level package, it's now lib.colorama. Some libraries might be fine with that, but for others, they expect to be able to import their own code using their normal names. If colorama.some_submodule tries to import colorama, it will fail.
It's important to realize that a statement like from lib import colorama doesn't change how colorama can be found everywhere. It only changes the local namespace. The package is still lib.colorama, we've just bound it to the name colorama in the current module.
As JonSG has suggested in comments, a better solution is to put the lib folder into the Python search path so that import colorama will find the package with its normal name. Modifying sys.path is one way to do that, another is the PYTHONPATH environment variable (probably not ideal for your current issue, but sometimes useful in other situations).
Related
I have a directory structure like below:
chatbot/
__init__.py
utils/
__init__.py
parser.py
nlu/
__init__.py
training/
__init__.py
module.py
I want to access parser.py from module.py.
I tried using this line from module.py:
from chatbot.utils import parser
And I got this error:
ModuleNotFoundError: No module named 'chatbot'
Any pointers to what I am doing wrong?
I am using python3 and trying to run the script as python3 nlu/training/module.py.
Thanks in advance!
I believe the right way of solving such problems is:
figure out what your top-level packages and modules are and in what directory they are
change to that directory
make all your imports absolute, i.e. always start with a top-level module or package (instead of things like from . import blah)
use the executable module (python -m) way of running your code, for example path/to/pythonX.Y -m top_level_package.executable_module (instead of path/to/pythonX.Y top_level_package/executable_module.py)
In case the top-level modules or packages are not all in the same directory:
Either work on packaging your libraries or applications correctly and install them in the site packages (eventually as editable, also known as develop mode).
Or, as a last resort, collect the other directories containing the top-level packages and modules in the PYTHONPATH environment variable like the following:
PYTHONPATH=path/to/alpha:path/to/bravo path/to/pythonX.Y -m top_level_package.executable_module
I was able to solve the issue by adding the parent directory of chatbot package to sys.path.
Say if chatbot python package is in /home/my_project/chatbot/, I added a statement like:
sys.path.append('/home/my_project') in module.py
This made all top-level python packages visible to all lower-level python packages.
I installed recordclass via pip3 install recordclass which installs it under /Users/timothee/homebrew/lib/python3.7/site-packages/recordclass; I'm trying to use it from a sublimetext package but it fails:
import sys
sys.path.append('/Users/timothee/homebrew/lib/python3.7/site-packages')
import recordclass
ImportError: No module named 'recordclass.mutabletuple'
If I instead use sys.path.append('/Users/timothee/homebrew/lib/python3.7/site-packages/recordclass') I get: SystemError: Parent module '' not loaded, cannot perform relative import
Note that it does work for some other pip3 installed modules, eg jstyleson, simplejson.
Here is contents of recordclass:
\ls
__init__.py arrayclass.py datatype.py mutabletuple.cpython-37m-darwin.so recordobject.cpython-37m-darwin.so test utils.py
__pycache__ dataobject.cpython-37m-darwin.so litelist.cpython-37m-darwin.so recordclass.py structclass.py typing
Not sure whether the reason is that sublime bundles its own python interpreter (3.3 IIRC) and my system python is 3.7, and it installs as recordobject.cpython-37m-darwin.so so can't be seen by sublime's python; but temporarily renaming to recordobject.cpython-33m-darwin.so didn't help.
Note: I've read other similar questions but these didn't help, eg:
* Install python module without PIP => not relevant; I can install it; just not load it from sublime
* Installing python modules like "Web3" without pip/pip3? ditto
* https://github.com/SublimeText/UnitTesting/issues/67
This is the most relevant post: Sublime Plugin: How can I import wx? but the solution there doesn't seem to work; since the problem seems to be these darwin.so files in my case
Okay, the scenario is very simple. I have this file structure:
.
├── interface.py
├── pkg
│ ├── __init__.py
│ ├── mod1.py
│ ├── mod2.py
Now, these are my conditions:
mod2 needs to import mod1.
both interface.py and mod2 needs to be run independently as a main script. If you want, think interface as the actual program and mod2 as an internal tester of the package.
So, in Python 2 I would simply do import mod1 inside mod2.py and both python2 mod2.py and python2 interface.py would work as expected.
However, and this is the part I less understand, using Python 3.5.2, if I do import mod1; then I can do python3 mod2.py, but python3 interface.py throws: ImportError: No module named 'mod1' :(
So, apparently, python 3 proposes to use import pkg.mod1 to avoid collisions against built-in modules. Ok, If I use that I can do python3 interface.py; but then I can't python3 mod2.py because: ImportError: No module named 'pkg'
Similarly, If I use relative import:
from . import mod1 then python3 interface.py works; but mod2.py says SystemError: Parent module '' not loaded, cannot perform relative import :( :(
The only "solution", I've found is to go up one folder and do python -m pkg.mod2 and then it works. But do we have to be adding the package prefix pkg to every import to other modules within that package? Even more, to run any scripts inside the package, do I have to remember to go one folder up and use the -m switch? That's the only way to go??
I'm confused. This scenario was pretty straightforward with python 2, but looks awkward in python 3.
UPDATE: I have upload those files with the (referred as "solution" above) working source code here: https://gitlab.com/Akronix/test_python3_packages. Note that I still don't like it, and looks much uglier than the python2 solution.
Related SO questions I've already read:
Python -- import the package in a module that is inside the same package
How to do relative imports in Python?
Absolute import module in same package
Related links:
https://docs.python.org/3.5/tutorial/modules.html
https://www.python.org/dev/peps/pep-0328/
https://www.python.org/dev/peps/pep-0366/
TLDR:
Run your code with python -m pkg.mod2.
Import your code with from . import mod1.
The only "solution", I've found is to go up one folder and do python -m pkg.mod2 and then it works.
Using the -m switch is indeed the "only" solution - it was already the only solution before. The old behaviour simply only ever worked out of sheer luck; it could be broken without even modifying your code.
Going "one folder up" merely adds your package to the search path. Installing your package or modifying the search path works as well. See below for details.
But do we have to be adding the package prefix pkg to every import to other modules within that package?
You must have a reference to your package - otherwise it is ambiguous which module you want. The package reference can be either absolute or relative.
A relative import is usually what you want. It saves writing pkg explicitly, making it easier to refactor and move modules.
# inside mod1.py
# import mod2 - this is wrong! It can pull in an arbitrary mod2 module
# these are correct, they uniquely identify the module
import pkg.mod2
from pkg import mod2
from . import mod2
from .mod2 import foo # if pkg.mod2.foo exists
Note that you can always use <import> as <name> to bind your import to a different name. For example, import pkg.mod2 as mod2 lets you work with just the module name.
Even more, to run any scripts inside the package, do I have to remember to go one folder up and use the -m switch? That's the only way to go??
If your package is properly installed, you can use the -m switch from anywhere. For example, you can always use python3 -m json.tool.
echo '{"json":"obj"}' | python -m json.tool
If your package is not installed (yet), you can set PYTHONPATH to its base directory. This includes your package in the search path, and allows the -m switch to find it properly.
If you are in the executable's directory, you can execute export PYTHONPATH="$(pwd)/.." to quickly mount the package for import.
I'm confused. This scenario was pretty straightforward with python 2, but looks awkward in python 3.
This scenario was basically broken in python 2. While it was straightforward in many cases, it was difficult or outright impossible to fix in any other cases.
The new behaviour is more awkward in the straightforward case, but robust and reliable in any case.
I had similar problem.
I solved it adding
import sys
sys.path.insert(0,".package_name")
into the __init__.py file in the package folder.
I'm in the process of learning how to package a python library using the official guide. I've started cloning the minimal sample package suggested in the guide here. I've then added the file my_module.py inside the folder sampleproject storing a simple power function. Another function is also stored in /sampleproject/sampleproject/__init__.py. The resulting structure of the library is the following
Finally, I've used pip to successfully install the package in the interpreter. The only thing left is to make sure that I'm able to run the functions stored in the subfolder sampleproject.
import sampleproject
sampleproject.main()
# Output
"Call your main application code here"
This is great. The package is able to run the function in __init__.py. However, the package is not able to find module.py:
import sampleproject
sampleproject.module
# Output
AttributeError: module 'sampleproject' has no attribute 'module'
I've tried to add __init__.py in the main folder and to change the settings in entry_points in setup.py without success. What should I let sampleproject to be able to find the function in module.py?
Your sampleproject.module is a function you would like to execute?
In this case, do as for the sampleproject, add () to execute it:
sampleproject.module()
Otherwise, you can import your package like this:
import sampleproject.module
or:
from sampleproject import module
To be clearer, you would have to import module in your sampleproject __init__.py. Then, when you want to use the package, import it (is some py file at root):
import sampleproject # is enough as it's going to import everything you stated in __init__.py
After that, you can start to use what's in the package you imported with maybe module() if you have a function called module in your package.
init.py discussions
it seems,
you are in sampleproject->module.py
so you need to try,
from sampleproject import module
Currently trying to work in Python3 and use absolute imports to import one module into another but I get the error ModuleNotFoundError: No module named '__main__.moduleB'; '__main__' is not a package. Consider this project structure:
proj
__init__.py3 (empty)
moduleA.py3
moduleB.py3
moduleA.py3
from .moduleB import ModuleB
ModuleB.hello()
moduleB.py3
class ModuleB:
def hello():
print("hello world")
Then running python3 moduleA.py3 gives the error. What needs to be changed here?
.moduleB is a relative import. Relative only works when the parent module is imported or loaded first. That means you need to have proj imported somewhere in your current runtime environment. When you are are using command python3 moduleA.py3, it is getting no chance to import parent module. You can:
from proj.moduleB import moduleB OR
You can create another script, let's say run.py, to invoke from proj import moduleA
Good luck with your journey to the awesome land of Python.
Foreword
I'm developing a project which in fact is a Python package that can be installed through pip, but it also exposes a command line interface. I don't have problems running my project after installing it with pip install ., but hey, who does this every time after changing something in one of the project files? I needed to run the whole thing through simple python mypackage/main.py.
/my-project
- README.md
- setup.py
/mypackage
- __init__.py
- main.py
- common.py
The different faces of the same problem
I tried importing a few functions in main.py from my common.py module. I tried different configurations that gave different errors, and I want to share with you with my observations and leave a quick note for future me as well.
Relative import
The first what I tried was a relative import:
from .common import my_func
I ran my application with simple: python mypackage/main.py. Unfortunately this gave the following error:
ModuleNotFoundError: No module named '__main__.common'; '__main__' is not a package
The cause of this problem is that the main.py was executed directly by python command, thus becoming the main module named __main__. If we connect this information with the relative import we used, we get what we have in the error message: __main__.common. This is explained in the Python documentation:
Note that relative imports are based on the name of the current module. Since the name of the main module is always __main__, modules intended for use as the main module of a Python application must always use absolute imports.
When I installed my package with pip install . and then ran it, it worked perfectly fine. I was also able to import mypackage.main module in a Python console. So it looks like there's a problem only with running it directly.
Absolute import
Let's follow the advise from the documentation and change the import statement to something different:
from common import my_func
If we now try to run this as before: python mypackage/main.py, then it works as expected! But, there's a caveat when you, like me, develop something that need to work as a standalone command line tool after installing it with pip. I installed my package with pip install . and then tried to run it...
ModuleNotFoundError: No module named 'common'
What's worse, when I opened a Python console, and tried to import the main module manually (import mypackage.main), then I got the same error as above. The reason for that is simple: common is no longer a relative import, so Python tries to find it in installed packages. We don't have such package, that's why it fails.
The solution with an absolute import works well only when you create a typical Python app that is executed with a python command.
Import with a package name
There is also a third possibility to import the common module:
from mypackage.common import my_func
This is not very different from the relative import approach, as long as we do it from the context of mypackage. And again, trying to run this with python mypackage/main.py ends similar:
ModuleNotFoundError: No module named 'mypackage'
How irritating that could be, the interpreter is right, you don't have such package installed.
The solution
For simple Python apps
Just use absolute imports (without the dot), and everything will be fine.
For installable Python apps in development
Use relative imports, or imports with a package name on the beginning, because you need them like this when your app is installed. When it comes to running such module in development, Python can be executed with the -m option:
-m mod : run library module as a script (terminates option list)
So instead of python mypackage/main.py, do it like this: python -m mypackage.main.
In addition to md-sabuj-sarker's answer, there is a really good example in the Python modules documentation.
This is what the docs say about intra-package-references:
Note that relative imports are based on the name of the current module. Since the name of the main module is always "__main__", modules intended for use as the main module of a Python application must always use absolute imports.
If you run python3 moduleA.py3, moduleA is used as the main module, so using the absolute import looks like the right thing to do.
However, beware that this absolute import (from package.module import something) fails if, for some reason, the package contains a module file with the same name as the package (at least, on my Python 3.7). So, for example, it would fail if you have (using the OP's example):
proj/
__init__.py (empty)
proj.py (same name as package)
moduleA.py
moduleB.py
in which case you would get:
ModuleNotFoundError: No module named 'proj.moduleB'; 'proj' is not a package
Alternatively, you could remove the . in from .moduleB import, as suggested here and here, which seems to work, although my PyCharm (2018.2.4) marks this as an "Unresolved reference" and fails to autocomplete.
Maybe you can do this before importing the module：
moduleA.py3
import os
import sys
sys.path.append(os.path.dirname(os.path.abspath(__file__)))
from moduleB import ModuleB
ModuleB.hello()
Add the current directory to the environment directory
Just rename the file from where you run the app to main.py:
from app import app
if __name__ == '__main__':
app.run()
import os
import sys
sys.path.append(os.path.dirname(os.path.abspath(__file__)))
will solve the issue of import path issue.