Episode 2: Python Roadmap – From Basics to APIs and Databases

Welcome back to our Python series!
In this episode, we’ll walk through a complete roadmap to mastering Python—from the fundamentals to more advanced topics like APIs and databases. Whether you’re new to coding or have some experience, this roadmap will guide your Python journey.

1. Python Basics

The foundation of everything you’ll do in Python starts here. These are the core concepts every Python developer must  :

a. Variables and Data Types

• Variables: Containers for storing data. In Python, you don’t need to declare the variable type; Python figures it out.
  • Example: x = 10, name = “Alice”
• Data Types: Understanding Python’s built-in types is crucial.
  • Strings (str): Text data, e.g., “Hello”.
  • Integers (int): Whole numbers, e.g., 42.
  • Floats (float): Decimal numbers, e.g., 3.14.
  • Lists: Ordered collection of items, e.g., [1, 2, 3].
  • Dictionaries: Key-value pairs, e.g., {“name”: “Alice”, “age”: 25}.
  • Sets: Unordered collection of unique items, e.g., {1, 2, 3}. Sets automatically remove duplicates and are useful when keeping unique elements.
  • Tuples: Ordered and immutable collection of items, e.g., (1, 2, 3). Unlike lists, tuples cannot be modified after they are created, making them useful for fixed data.

b. Control Flow

• Conditional Statements: Using if, elif, and else to control the flow of your programs.

Example:
if x > 10:

    print(“x is greater than 10”)

elif x == 10:

    print(“x is 10”)

else:

    print(“x is less than 10”)

 

• Loops:

For Loop: Iterates over a sequence (list, string, etc.).
for item in my_list:

    print(item)

 

While Loop: Repeats as long as a condition is true.
while x < 10:

    print(x)

    x += 1

c. Functions

• A function is a reusable block of code that performs a specific task.

Example:
def greet(name):

    return “Hello ” + name

 

print(greet(“Alice”)) # call the function.

• Functions help you organize your code and make it reusable.

d. Modules and Libraries

• Modules: Files containing Python definitions and statements. Python has many built-in modules.

Example:
import math

print(math.sqrt(16))  # Output: 4.0

 

• External Libraries: Packages like numpy, pandas, and requests that extend Python’s capabilities. You can install them using pip.

2. Object-Oriented Programming (OOP)

After learning the basics, it’s important to understand Object-Oriented Programming. OOP allows you to organize your code better, especially in large projects.

a. Classes and Objects

• Class: A blueprint for creating objects. Objects are instances of classes.

Example:
class Dog:

    def __init__(self, name):

        self.name = name

 

    def bark(self):

        return self.name + ” says Woof!”

 

my_dog = Dog(“Buddy”)

print(my_dog.bark())

• __init__: A special method called a constructor is used to initialize the object’s state.
• self: Refers to the instance of the object itself.

b. Inheritance

• Inheritance allows you to define a class that inherits all the methods and properties from another class.

Example:
class Animal:

    def __init__(self, name):

        self.name = name

    def speak(self):

        pass

class Dog(Animal):

    def speak(self):

        return self.name + ” says Woof!”

 

c. Polymorphism

• Polymorphism allows different classes to be treated as instances of the same class through inheritance.

Example:
class Cat(Animal):

    def speak(self):

        return self.name + ” says Meow!”

3. Working with APIs

APIs are an essential skill in modern programming. APIs allow your Python program to interact with other services, fetching or sending data over the internet.

a. What is an API?

• An API (Application Programming Interface) allows different applications to communicate with each other. You can use APIs to retrieve data from websites or services like Twitter, GitHub, or Google Maps.

b. Using the requests Library

• The requests library in Python makes it easy to send HTTP requests to interact with web services.

Example: Sending a GET request to retrieve data from an API.
import requests

response = requests.get(‘https://api.example.com/data’)

print(response.json())

c. Interacting with APIs

• GET Requests: Used to fetch data.
• POST Requests: Used to send data.
• Authentication: Many APIs require authentication through API keys or tokens.

d. Practical API Use Case

Example: Fetching weather data from an API.

import requests

api_key = ‘your_api_key’

city = ‘London’

response = requests.get(f”http://api.weatherapi.com/v1/current.json?key={api_key}&q={city}”)

weather_data = response.json()

print(weather_data)

4. Database Integration

Working with databases allows you to store, retrieve, and manipulate large amounts of data efficiently. Python provides several ways to interact with both SQL and NoSQL databases.

a. SQL Databases

• SQLite: A lightweight SQL database that comes built-in with Python. You can use the sqlite3 module to work with SQLite databases.

Example:

import sqlite3

connection = sqlite3.connect(‘example.db’)

cursor = connection.cursor()

 

cursor.execute(”’CREATE TABLE IF NOT EXISTS users (id INTEGER PRIMARY KEY, name TEXT)”’)

cursor.execute(”’INSERT INTO users (name) VALUES (‘Alice’)”’)

 

connection.commit()

connection.close()

b. PostgreSQL and MySQL

• You can use libraries like psycopg2 (for PostgreSQL) or mysql-connector-python to connect Python to larger SQL databases.

c. NoSQL Databases (MongoDB)

• MongoDB is a NoSQL database that stores data in JSON-like documents. You can use the pymongo library to work with MongoDB in Python.

Example:

from pymongo import MongoClient

client = MongoClient(‘mongodb://localhost:27017/’)

db = client[‘mydatabase’]

collection = db[‘users’]

collection.insert_one({‘name’: ‘Alice’})

5. Web Development and APIs with Flask/Django

After learning about APIs and databases, you can integrate them into web applications.

a. Flask and Django Frameworks

• Flask: A lightweight web framework that allows you to quickly build web applications.

Example:
from flask import Flask

app = Flask(__name__)

 

@app.route(‘/’)

def home():

    return “Hello, Flask!”

 

if __name__ == ‘__main__’:

    app.run(debug=True)

• Django: A full-featured web framework that includes everything you need to build large-scale web applications.

b. Building REST APIs

• You can use Flask or Django to create your own RESTful APIs, allowing other services or applications to interact with your web app.

c. Database-Driven Web Apps

• Connect your Flask/Django app to a database to store and manage data, like user accounts, products, or posts.

6. Advanced Topics

Once you’ve mastered APIs and databases, you can move on to more advanced topics.

a. Testing and Debugging

• Learn how to write tests using frameworks like unittest or pytest to ensure your code works as expected.
• Use debugging tools like pdb to step through your code.

b. Concurrency and Parallelism

• Learn how to perform tasks concurrently using Python’s asyncio library or multithreading with the threading module.

c. Deployment

• Learn how to deploy your Python applications to the cloud using platforms like Heroku, AWS, or DigitalOcean.

Wrap-up

This roadmap gives you a complete path to mastering Python, from basic syntax to advanced topics like APIs and databases. In future episodes, we’ll deep-dive into each section, giving you step-by-step guidance.

Stay tuned for the next episode, where we’ll begin setting up your Python environment and writing your first code!