How to automatically install required packages from a python script as necessary?

How to automatically install required packages from a python script as necessary?

Let's assume that your Python script is example.py:

import osimport timeimport sysimport fnmatchimport requestsimport urllib.requestfrom bs4 import BeautifulSoupfrom multiprocessing.dummy import Pool as ThreadPool print('test')

You can use pipreqs to automatically generate a requirements.txt file based on the import statements that the Python script(s) contain. To use pipreqs, assuming that you are in the directory where example.py is located:

pip install pipreqspipreqs .

It will generate the following requirements.txt file:

requests==2.23.0beautifulsoup4==4.9.1

which you can install with:

pip install -r requirements.txt

The best way I know is, create a file requirements.txt list out all the packages name in it and install it using pip

pip install -r requirements.txt

Example requirements.txt:

BeautifulSoup==3.2.0Django==1.3Fabric==1.2.0Jinja2==2.5.5PyYAML==3.09Pygments==1.4SQLAlchemy==0.7.1South==0.7.3amqplib==0.6.1anyjson==0.3...

You can use setuptools to install dependencies automatically when you install your custom project on a new machine. Requirements file works just fine if all you want to do is to install a few PyPI packages.

Here is a nice comparison between the two. From the same link you can see that if your project has two dependent packages A and B, all you have to include in your setp.py file is a line

install_requires=[   'A',   'B'] 

Of course, setuptools can do much more. You can include setups for external libraries (say C files), non PyPI dependencies, etc. The documentation gives a detailed overview on installing dependencies. There is also a really good tutorial on getting started with python packaging.

From their example, a typical setup.py file would look like this.

from setuptools import setupsetup(name='funniest',      version='0.1',      description='The funniest joke in the world',      url='http://github.com/storborg/funniest',      author='Flying Circus',      author_email='flyingcircus@example.com',      license='MIT',      packages=['funniest'],      install_requires=[          'markdown',      ],      zip_safe=False)

In conclusion, it is so simple to get started with setuptools. This package can make it fairly easy to migrate your code to a new machine.