How to Automatically Install Required Packages from a Python Script as Necessary

Is there a way to automatically install required packages in Python?

Node has npm similarly python having pip

pip is a package management system used to install and manage software
packages written in Python.

So first you need to install pip,

sudo apt-get install python-pip

You have to keep your requirements in requirements.txt in you project folder as like package.json in nodejs.

eg:

pip install package1
pip install package2
pip install package3

Then move on to your project path, then do this:

pip install -r requirements.txt

How do I automatically install missing python modules?

Installation issues are not subject of the source code!

You define your dependencies properly inside the setup.py of your package
using the install_requires configuration.

That's the way to go...installing something as a result of an ImportError
is kind of weird and scary. Don't do it.

How to use requirements.txt to install all dependencies in a python project

If you are using Linux OS:

Remove matplotlib==1.3.1 from requirements.txt
Try to install with sudo apt-get install python-matplotlib
Run pip install -r requirements.txt (Python 2), or pip3 install -r requirements.txt (Python 3)
pip freeze > requirements.txt

If you are using Windows OS:

python -m pip install -U pip setuptools
python -m pip install matplotlib

Automatically create requirements.txt

Use Pipenv or other tools is recommended for improving your development flow.

pip3 freeze > requirements.txt  # Python3
pip freeze > requirements.txt  # Python2

If you do not use a virtual environment, pigar will be a good choice for you.

Is there any way to automatic detect required modules and packages in my own python project

Usually people know their requirements by having separate virtual environments with required modules installed. In this case, it is trivial to make the requirements.txt file by running the following while being inside the virtual environment:

pip freeze > requirements.txt

Also, to avoid surprises in production and be confident about the code you have, would be good to have tests and a good test coverage. In case, there is a module imported but not installed, tests would show it.

Another way to find modules that cannot be imported is by using pylint static code analysis tool against the package. There is a special F0401 - Unable to import %s warning.

Demo:

imagine you have a test.py file that has a single import statement
```
import pandas
```
pandas module is not installed in the current python environment

here is the output of pylint test.py:

$ pylint test.py
No config file found, using default configuration
************* Module test
C:  1, 0: Missing module docstring (missing-docstring)
F:  1, 0: Unable to import 'pandas' (import-error)
W:  1, 0: Unused import pandas (unused-import)

How to make a Python exe file automatically install dependancies?

When making the executable you should declare the modules with it, you can then just copy the library files to the same location as the programme.

I use cx_freeze when making exe's and an example setup.py files looks like this:

from cx_Freeze import setup, Executable

base = None    

executables = [Executable("projectname.py", base=base)]

packages = ["idna","os","shutil","csv","time","whatever else you like"]
options = {
    'build_exe': {    
        'packages':packages,
    },    
}

setup(
    name = "Some Project",
    options = options,
    version = "1.2.3",
    description = 'Generic Description',
    executables = executables
)

Packages are where the modules are declared.

If you have a quick search online it'll give you complete guides for it, all you'd need to do then is copy the lot across to your friend's computer.

Hope this helps!