PEP 8 & Linting: Keeping Your Code Clean

Code is read much more often than it is written. In a data science team, readability is paramount. If your colleague (or your future self) cannot read your code, the analysis is useless.

PEP 8: The Style Guide

python has an official style guide called PEP 8. It dictates how your code should look.

• Use 4 spaces for indentation.
• Snake_case for functions and variables (my_function, not myFunction).
• CamelCase for classes (MyClass).
• Spaces around operators (x = 1, not x=1).

You don't need to memorize the whole document. Tools can help you.

Linters: The Automated Code Reviewers

A linter analyzes your code for programmatic and stylistic errors before you run it.

Common Linters

1. Flake8: Checks for PEP 8 compliance and logic errors (like unused imports or undefined variables).
2. Pylint: very strict, catches more errors but can be noisy.
3. Ruff: The new kid on the block. Written in Rust, it is incredibly fast and combines features of Flake8, isort, and others.

Example of what a linter catches:

import pandas as pd # Linter: imported but unused
x=1                 # Linter: missing whitespace around operator
def MyFunc():       # Linter: function name should be lowercase
  print(x)

Formatters: The Auto-Fixers

While linters tell you what's wrong, formatters fix it for you automatically.

Black: The Uncompromising Code Formatter

Black is the industry standard. It formats your code so you don't have to decide. It reshapes your code to be PEP 8 compliant.

Before Black:

def very_long_function_name(parameter_one, parameter_two, parameter_three, parameter_four): print(parameter_one)

After Black:

def very_long_function_name(
    parameter_one, parameter_two, parameter_three, parameter_four
):
    print(parameter_one)

How to Set This Up

1. Install the tools:

   pip install ruff black
   

2. Run them:

   # Check for errors
   ruff check .
   
   # Format code
   black .
   

3. VS Code Integration: Install the "Ruff" and "Black Formatter" extensions in VS Code. Enable "Format on Save" in your settings.

Summary

• Style Guide: Follow PEP 8.
• Linter (Ruff/Flake8): Finds bugs and style violations.
• Formatter (Black): Automatically fixes style violations.

Adopting these tools removes the mental load of formatting, letting you focus on the logic and the data.