Installing Packages in Python

Beyond the Standard Library and your own modules, Python supports external packages — reusable code written by the community or third-party developers.

To manage external packages, Python uses:

pip — Python’s built-in package installer PyPI — The Python Package Index, a large repository of open-source Python packages

What Is pip?

• pip is the official package manager for Python.
• It allows you to download, install, upgrade, and remove packages from PyPI.
• You can use pip directly from the command line.

Installing a Package

Basic Syntax:

pip install package_name

Example 1: Install requests Package

pip install requests

Explanation:

• Installs the popular requests library for working with HTTP.

Example 2: Using Installed Package

import requests
 
response = requests.get('https://api.github.com')
print("Status Code:", response.status_code)

Status Code: 200

Checking Installed Packages

pip list

Explanation:

• Lists all installed packages and their versions.

Upgrading a Package

pip install --upgrade package_name

Example:

pip install --upgrade requests

Uninstalling a Package

pip uninstall package_name

Example:

pip uninstall requests

Installing a Specific Version

pip install package_name==version_number

Example:

pip install Django==4.2.0

Using a requirements.txt File

In larger projects, you often maintain a list of required packages:

File: requirements.txt

requests==2.31.0
Django>=4.2
pandas

Install all at once:

pip install -r requirements.txt

Virtual Environments

For managing project-specific dependencies, it’s best to use a virtual environment:

python -m venv venv
source venv/bin/activate  # On Linux/macOS
venv\Scripts\activate     # On Windows

Then:

pip install package_name

Summary

• Use pip to install external packages from PyPI.
• Installed packages can be used via import.
• You can install, upgrade, or uninstall packages easily.
• Manage dependencies cleanly with virtual environments and requirements.txt.

Next, we will explore Object-Oriented Programming (OOP) — a core part of writing organized, scalable Python code.