1. Project Development

Applying Learned Concepts to Real-World Projects

To solidify Python skills, work on projects that incorporate:

• Data processing (Pandas, NumPy)
• Web development (Flask/Django)
• Automation (Scripting)
• Machine Learning (scikit-learn, TensorFlow)

Example Project: Task Manager (CLI)

# task_manager.py
import json
from typing import List, Dict

class TaskManager:
    def __init__(self, filename: str = "tasks.json"):
        self.filename = filename
        self.tasks = self._load_tasks()

    def _load_tasks(self) -> List[Dict]:
        try:
            with open(self.filename, "r") as f:
                return json.load(f)
        except FileNotFoundError:
            return []

    def _save_tasks(self):
        with open(self.filename, "w") as f:
            json.dump(self.tasks, f, indent=4)

    def add_task(self, title: str, priority: int = 1):
        self.tasks.append({"title": title, "priority": priority, "done": False})
        self._save_tasks()

    def list_tasks(self):
        for idx, task in enumerate(self.tasks):
            status = "✓" if task["done"] else " "
            print(f"{idx + 1}. [{status}] {task['title']} (Priority: {task['priority']})")

    def mark_done(self, task_id: int):
        if 0 <= task_id < len(self.tasks):
            self.tasks[task_id]["done"] = True
            self._save_tasks()

if __name__ == "__main__":
    manager = TaskManager()
    manager.add_task("Learn Python", priority=2)
    manager.add_task("Build a project")
    manager.list_tasks()

Project Planning & Execution

1. Define Requirements
   • What problem does it solve?
   • Who is the user?
2. Break Down Tasks
   • Use GitHub Issues or Trello
3. Set Milestones
   • Example: "Basic CLI by Week 1"
4. Iterate & Improve

Version Control with Git

# Initialize repository
git init

# Check status
git status

# Add files
git add .

# Commit changes
git commit -m "Add task manager CLI"

# Push to remote (GitHub/GitLab)
git remote add origin <repo-url>
git push -u origin main

2. Code Style & Best Practices

PEP 8 Style Guide

Python's official style guide enforces consistency.

Key Rules

Example: PEP 8 Compliant Code

# Good PEP 8 compliant code
import os
from typing import List

def calculate_average(numbers: List[float]) -> float:
    """Compute the arithmetic mean of a list."""
    return sum(numbers) / len(numbers)

Check PEP 8 Compliance

pip install pycodestyle
pycodestyle script.py

Code Readability & Maintainability

1. Modularize Code
   • Split into functions/classes
   • One responsibility per function
2. Avoid Magic Numbers

   # Bad
   if temperature > 100:
       alert()
   
   # Good
   BOILING_POINT = 100
   if temperature > BOILING_POINT:
       alert()

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3. Use Constants

   MAX_RETRIES = 3
   API_TIMEOUT = 30  # seconds

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Docstrings

Describe what functions/classes do (following Google style):

def factorial(n: int) -> int:
    """Calculates the factorial of a non-negative integer.
    
    Args:
        n: Input number (must be ≥ 0).
    
    Returns:
        Factorial of n.
    
    Raises:
        ValueError: If n is negative.
    """
    if n < 0:
        raise ValueError("n must be non-negative")
    return 1 if n == 0 else n * factorial(n - 1)

Generate Documentation

pip install pdoc
pdoc --html my_module.py

Code Reviews

1. Checklist:
   • Does it work as intended?
   • Is the code readable?
   • Are there edge cases?
2. Tools:
   • GitHub Pull Requests
   • pylint for static analysis

     pip install pylint
     pylint script.py

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3. Deployment Basics

Options for Deploying Python Apps

Example: Deploying a Flask App on Heroku

1. Project Structure

   myapp/
   ├── app.py
   ├── requirements.txt
   ├── Procfile
   └── runtime.txt

2. app.py

   from flask import Flask
   app = Flask(__name__)
   
   @app.route("/")
   def home():
       return "Hello, World!"
   
   if __name__ == "__main__":
       app.run()

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3. requirements.txt

   flask
   gunicorn

4. Procfile

   web: gunicorn app:app

5. Deploy Steps

   heroku login
   heroku create my-flask-app
   git push heroku main

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Virtual Environments

Isolate dependencies per project:

python -m venv venv
source venv/bin/activate  # Linux/Mac
venv\Scripts\activate     # Windows
pip install -r requirements.txt

Summary Table

Final Tips

• ✅ Start small, then scale
• ✅ Write tests early (TDD)
• ✅ Automate deployments (CI/CD)
• ✅ Document everything

This guide equips you to develop, refine, and deploy Python projects professionally! 🚀