PEP8 – Python Coding Standard and Best Practices

PEP 8 stands for Python Enhancement Proposal 8 — it is the official style guide for writing Python code. Following PEP 8 makes your Python code consistent, readable, and maintainable, especially when working in teams.

Here’s a detailed breakdown:

---

1. Indentation

• Use 4 spaces per indentation level (not tabs).

# Bad
def add(a,b):
  return a+b

# Good
def add(a, b):
    return a + b

---

2. Line Length

• Limit lines to 79 characters (for code) and 72 for docstrings/comments.

# Bad
print("This is a very long line that exceeds the recommended 79 characters limit in PEP8")

# Good
print(
    "This is a line wrapped properly according to PEP8 recommendations"
)

---

3. Blank Lines

• Top-level functions/classes: 2 blank lines before

• Methods inside a class: 1 blank line before

class MyClass:
    def method1(self):
        pass

    def method2(self):
        pass


def top_level_function():
    pass

---

4. Imports

• Imports should usually be on separate lines and ordered:

1. Standard library
2. Third-party libraries
3. Local application imports

# Bad
import sys, os, requests

# Good
import os
import sys

import requests

from mymodule import myfunction

---

5. Spaces in Expressions

• Avoid extra spaces:

# Bad
x = 1 + 2
y = 3* 4
z = ( 5 + 6 )

# Good
x = 1 + 2
y = 3 * 4
z = (5 + 6)

---

6. Naming Conventions

---

7. String Quotes

• Either single ' or double " quotes are fine, be consistent.

# Bad
string1 = "Hello"
string2 = 'World'

# Good
string1 = "Hello"
string2 = "World"

---

8. Function Annotations (Optional but Recommended)

• Include type hints for clarity:

def greet(name: str) -> str:
    return f"Hello, {name}"

---

9. Comments

• Use complete sentences, capitalize first letter, avoid obvious comments.

# Bad
x = x + 1  # increment x

# Good
# Adjust index to match 1-based numbering
index += 1

---

10. Example Putting It All Together

import os
import sys

from mymodule import calculate_sum


PI = 3.14159  # Constant

class Circle:
    def __init__(self, radius: float):
        self.radius = radius

    def area(self) -> float:
        """Calculate area of the circle."""
        return PI * self.radius ** 2


def main():
    circle = Circle(5)
    print(f"Area: {circle.area()}")


if __name__ == "__main__":
    main()

---

Summary

-------------

PEP 8 ensures your code is:

• Readable → others (and future you) can understand it

• Consistent → same rules across projects and teams

• Maintainable → easier to debug, refactor, and extend