Python Tutorial: Setting up your environment

There are two main ways I reccommend to install python

• from the python site https://www.python.org/
  • python basic package manager is pip you can use it from any command line of your operative system
  • when using base python I recommend to create independent virtual environments for each project, this will help you keep track of the packages you are using and also avoid issues with multiple package versions; the following commands refer to a linux bash command line, you can find windows equivalent in the virtual environment documentation
    1. install venv with the following command

       pip install venv
       

    2. create a project directory and change your current directory into it

           mkdir myproject
           cd myproject
       

    3. create a virtual environment in the project directory

           python -m venv .
       

    4. activate it

           source bin/activate
       

• using the miniconda from Continuum https://docs.conda.io/en/latest/miniconda.html
  • this package and environment manager allows you to easily create independent projects, keeping separate package environments as well as using separate python interpreters
  • when using Miniconda I also recommend to create separate environments for each project and avoid using the base environment which hosts the package manager itself
    1. create a virtual environment with the python version of your choice

           conda create -n myenv python=3.10
       

    2. create your project directory and move into it
    3. activate your conda environment

       conda activate myenv
       

One of python slogans is to be a “Battery Included” language: this means that a lot of interesting functionalities are installed by default. Most of this tutorial will make use of the default library; however I found some convenient libraries which are used for exercises and examples.

• pytest helps executing unit tests in a very convenient way
• pytest-xdist executes many tests in parallel
• pytest-cov creates a coverage report which is very useful
• python-language-server is a language server which will enable your programming editor to help you with development
• black is a formatter, useful for mantaining a readable code style which is also version control friendly
• pylint code linter, will help you find issues in your code witout running it
• jupyterlab a great multilanguage development environment in your browser; used by Google Cloud and many others

Here is some other software which will help you developing in python

• Visual Studio Code free editor by Microsoft, one of the best around
  • This tutorial will help you getting started with Visual Studio Code and python
• GIT one of the most used version control system, created by Linus Torvalds

Python provides a basic interactive command line to start with, I recommend to play with it and possibly with all of its extensions. The command line reads the python expressions or statements, evaluates or executes them respectively and prints the result; these interactive command lines are called also Read, Eval, Print Loops (REPL) and were available since the LISP language. to start the python REPL open your command line, move into your project, activate it and type this will print some version information and the basic python prompt >>> You can type here python expressions, when you hit return python will evaluate them and print their value. It is possible to type whole programs into a REPL (which is not the most convenient way); I love it because it gives me a fast feedback. In time many extensions to the python CLI where developed which have some advantages, here is a list of some:

• ipython
• ptipython (which adds some CLI and editing functionalities)
• jupyter notebook (web powered extension)
• jupyter lab (even more powerful)

Sometime I use one of the last three to make quick prototypes and tests as they can save what I typed in a file.