Python

About

Python is an interpreted, high-level and general-purpose programming language. Python's design philosophy emphasizes code readability with its notable use of significant whitespace. Its language constructs and object-oriented approach aim to help programmers write clear, logical code for small and large-scale projects. (Wikipedia, 2020)

• https://www.python.org/

Getting Started

• https://www.python.org/about/gettingstarted/
• We highly recommend you to install and get familiar with the following tools before starting to work with python productively, they will save you a lot of time and problems.

Pyenv (Python Version Management)

Manage multiple python versions comfortably

Installation

MacOS

1. Install via [Homebrew](https://brew.sh)

   brew update
   brew install pyenv

2. Add pyenv init to your shell to enable shims and autocompletion. Please make sure eval "$(pyenv init -)" is placed toward the end of the shell configuration file since it manipulates PATH during the initialization.

   echo -e 'if command -v pyenv 1>/dev/null 2>&1; then\n  eval "$(pyenv init -)"\nfi' >> ~/.zshrc

   Bash note: Modify your ~/.bash_profile file instead of ~/.zshrc.
3. Restart shell

   source ~/.zshrc

Debian based Linux

1. Install dependencies

   sudo apt install -y make build-essential libssl-dev zlib1g-dev  libbz2-dev libreadline-dev libsqlite3-dev wget curl llvm libncurses5-dev libncursesw5-dev xz-utils   tk-dev libffi-dev liblzma-dev python-openssl git

2. Clone the repository

   git clone https://github.com/pyenv/pyenv.git ~/.pyenv

3. Update .bashrc

   echo 'export PYENV_ROOT="$HOME/.pyenv"' >> ~/.bashrcnano
   echo 'export PATH="$PYENV_ROOT/bin:$PATH"' >> ~/.bashrc
   echo -e 'if command -v pyenv 1>/dev/null 2>&1; then\n eval "$(pyenv init --path)"\nfi' >> ~/.bashrc

Download specific python version

pyenv install 3.7.0

List available python versions

pyenv versions

Activate a specific version locally

This sets the Python version for the current folder and all subfolders.

pyenv local 3.7.0

Activate a specific version globally

pyenv global 3.7.0

Virtual environments

Don't clutter your global pip installation, use one virtual environment per project instead. \ Important: Create virtual environment in project folder

Create a virtual environment & activate it

python3 -m venv venv
source venv/bin/activate

Deactivate virtual environment

deactivate

Create a requirements file

pip freeze > requirements.txt

Install dependencies from a requirements file

pip install -r requirements.txt

Uninstall virtual environment

1. (Optionally) Deactivate venv

   deactivate

2. Remove venv folder

   rm -rf venv

Useful snippets

Format String

text="This"

print("{} {} {} {}!".format(text, 'is', 'super', 'cool')

> This is super cool!

Debug with ic() instead of print()

• Use https://github.com/gruns/icecream

  pip install icecream

  >>> a = 6
  >>> def half(i):
  >>>     return i / 2
  >>> b = half(ic(a))
  ic| a: 6
  >>> ic(b)
  ic| b: 3