Installing Python and Setting Up Environment

# Installing Python and Setting Up Environment

Welcome to Chapter 2! Now that you know what Python is and why it's amazing, it's time to install it on your computer and set up a professional development environment. By the end of this chapter, you'll have Python running and will have executed your first script.

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1. Introduction #

Before you can write Python code, you need two things:

1. 1. Python itself — the interpreter that runs your code.

1. 2. A code editor or IDE — a tool where you write your code comfortably.

Think of it like cooking: Python is the stove, and the IDE is your fully equipped kitchen with cutting boards, knives, and utensils. You *could* cook with just a stove, but a full kitchen makes everything easier and more efficient.

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2. Learning Objectives #

By the end of this chapter, you will be able to:

• Download and install Python on Windows, macOS, and Linux.

• Verify the Python installation via the command line.

• Understand what pip is and how to use it.

• Set up VS Code as your primary Python IDE.

• Understand PyCharm basics.

• Write and run your first Python script.

• Use the Python interactive shell (REPL).

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3. Installing Python on Windows #

Step 1: Download Python #

1. 1. Go to https://www.python.org/downloads/

1. 2. Click the big yellow "Download Python 3.x.x" button.

Step 2: Run the Installer #

1. 1. Double-click the downloaded .exe file.

1. 2. ⚠️ CRITICAL: Check the box that says "Add Python to PATH" at the bottom of the installer. This is the most common mistake beginners make!

1. 3. Click "Install Now".

Windows Installer Screen:
┌──────────────────────────────────────────┐
│  Install Python 3.12.x                   │
│                                          │
│  [x] Install launcher for all users      │
│  [✅] Add Python 3.12 to PATH  ← CHECK! │
│                                          │
│  [ Install Now ]  [ Customize ]          │
└──────────────────────────────────────────┘

Step 3: Verify Installation #

python --version

Expected Output:

Python 3.12.x

Also verify pip (Python's package manager):

pip --version

Expected Output:

pip 24.x.x from ... (python 3.12)

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4. Installing Python on macOS #

Option 1: Using the Official Installer #

1. 1. Visit python.org/downloads.

1. 2. Download the macOS installer (.pkg file).

1. 3. Run the installer and follow the prompts.

Option 2: Using Homebrew (Recommended) #

# Install Homebrew if not installed
/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

# Install Python
brew install python

Verify Installation #

python3 --version
pip3 --version

> Note: On macOS, you may need to use python3 and pip3 instead of python and pip.

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5. Installing Python on Linux #

Most Linux distributions come with Python pre-installed. To check:

python3 --version

If not installed, use your package manager:

Ubuntu / Debian #

sudo apt update
sudo apt install python3 python3-pip

Fedora #

sudo dnf install python3 python3-pip

Arch Linux #

sudo pacman -S python python-pip

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6. Understanding pip #

pip stands for "Pip Installs Packages" and is Python's official package manager. It lets you install third-party libraries from the Python Package Index (PyPI).

# Install a package
pip install requests

# Install a specific version
pip install requests==2.31.0

# Upgrade a package
pip install --upgrade requests

# List installed packages
pip list

# Uninstall a package
pip uninstall requests

Common Useful Packages #

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7. Python IDEs and Code Editors #

7.1 VS Code (Recommended for Beginners) #

Visual Studio Code is a free, lightweight, and powerful code editor by Microsoft. It's the most popular editor for Python development.

Installation:

1. 1. Download from code.visualstudio.com

1. 2. Install and open VS Code.

1. 3. Go to Extensions (Ctrl+Shift+X).

1. 4. Search for "Python" by Microsoft and click Install.

VS Code Python Extension:
┌────────────────────────────────────────┐
│  🐍 Python (Microsoft)                │
│  ★★★★★  (45M+ downloads)              │
│                                        │
│  Features:                             │
│  • IntelliSense (auto-completion)      │
│  • Debugging                           │
│  • Linting (error detection)           │
│  • Jupyter Notebook support            │
│  • Virtual environment support         │
│                                        │
│  [ Install ]                           │
└────────────────────────────────────────┘

Recommended VS Code Extensions for Python:

• Python (by Microsoft) — Core Python support

• Pylance — Fast, feature-rich language server

• Python Debugger — Debugging support

• Code Runner — Run code with one click

7.2 PyCharm #

PyCharm by JetBrains is a full-featured Python IDE.

• Community Edition — Free, open-source (great for learning).

• Professional Edition — Paid, with web development and database tools.

Installation:

1. 1. Download from jetbrains.com/pycharm.

1. 2. Install the Community Edition.

1. 3. Create a new project and start coding.

7.3 Other Options #

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8. The Python Interactive Shell (REPL) #

Python comes with an interactive shell called the REPL (Read-Eval-Print Loop). It lets you execute Python code line by line — perfect for quick experiments.

How to Open: #

python

You'll see something like:

Python 3.12.x (main, ...)
Type "help", "copyright", "credits" or "license" for more information.
>>>

Try It: #

```python id="py2_repl1" >>> print("Hello from the Python shell!") Hello from the Python shell!

>>> 2 + 2 4

>>> name = "Alice" >>> print(f"Welcome, {name}!") Welcome, Alice!

>>> exit() # To leave the shell

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## 9. Writing and Running Your First Python Script

### Step 1: Create a File
Open VS Code and create a new file called `hello.py`.

### Step 2: Write the Code

python id="py2_ex1" # hello.py — Your very first Python script! print("Hello, World!") print("I am learning Python!") print("This is my first script! 🎉")

### Step 3: Run the Script

**Option 1: Using the Terminal**

bash python hello.py

**Option 2: Using VS Code**
- Click the **▶ Play button** in the top-right corner of VS Code.
- Or press **Ctrl+F5** (Run Without Debugging).

**Output:**

Hello, World! I am learning Python! This is my first script! 🎉

---

## 10. Understanding Python File Structure

Your Python file (.py): ┌──────────────────────────────────┐ │ # Comments (notes for humans) │ │ # They start with # │ │ │ │ import math ← Module imports │ │ │ │ name = "Alice" ← Variables │ │ age = 25 │ │ │ │ def greet(): ← Functions │ │ print(f"Hi, {name}!") │ │ │ │ greet() ← Function call │ └──────────────────────────────────┘

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## 11. Code Examples

### Example 1: Using Multiple Print Statements

python id="py2_ex2" print("=" * 40) print(" Python Installation Successful!") print("=" * 40)

**Output:**

======================================== Python Installation Successful! ========================================

### Example 2: Quick Math in Python

python id="py2ex3" # mathtest.py import math

radius = 5 area = math.pi * radius ** 2 print(f"Area of circle with radius {radius}: {area:.2f}")

**Output:**

Area of circle with radius 5: 78.54

### Example 3: Checking Your Python Environment

python id="py2ex4" # environmentinfo.py import sys import platform

print(f"Python Version : {sys.version}") print(f"Platform : {platform.system()} {platform.release()}") print(f"Architecture : {platform.architecture()[0]}") print(f"Processor : {platform.processor()}") ``

1. 1. Not adding Python to PATH: If python --version doesn't work, you likely forgot to check "Add to PATH" during installation. Reinstall and check the box.

1. 2. Using python vs python3: On macOS/Linux, python might point to Python 2. Always use python3.

1. 3. Saving files without .py extension: Your files must end in .py for Python to recognize them.

1. 4. Running code in the wrong directory: Make sure your terminal is in the same directory as your .py file.

1. 3. Create a file called myinfo.py that prints your name, age, and favorite hobby.

Q8: Which command installs a package using pip? A) pip get requests B) pip download requests C) pip install requests D) pip add requests Answer: C — pip install packagename is the correct command.

Q10: How do you exit the Python REPL? A) quit B) stop() C) exit() D) close() Answer: C — Type exit() or quit() to leave the REPL.

Q: Can I have multiple versions of Python installed? A: Yes. Use tools like pyenv to manage multiple Python versions easily.

Q: What is the difference between python and python3 commands? A: On some systems, python refers to Python 2. The python3 command explicitly calls Python 3. On modern Windows installations, python usually points to Python 3.

• Python files use the .py extension and are run with python filename.py.

You've successfully installed Python and set up your development environment. Now it's time to write real code! In Chapter 3: Python Syntax and First Program, we'll learn Python's syntax rules, understand indentation, explore comments, master the print()` function, and build a simple calculator. Let's code! 🚀