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Tutorial 9: Installing Python and Python IDEs

Learning Objective

To be able to install Python and required Python IDEs on the computer. Get Python and Python IDEs running for the learning activities included in this course.

9.1 Introduction: Setting Up Your Digital Workspace

Before you can write your first line of Python code, you need to set up your programming environment. This is the first practical hurdle every developer faces. Unlike many tutorials that gloss over installation issues, this guide provides detailed, step-by-step instructions for Windows, macOS, and Linux. More importantly, you will learn why certain steps (like adding Python to the PATH) are critical, and you will set up an Integrated Development Environment (IDE) that will make your coding journey smoother. By the end of this tutorial, you will be ready to write and run Python scripts on your own machine.

9.2 Installing Python: Platform-Specific Guides

Python is cross-platform, but the installation process differs across operating systems. Follow the guide for your specific OS.

9.2.1 Windows Installation

1. Download the Installer:

   • Go to python.org/downloads.
   • Click the big yellow "Download Python 3.12.x" (or later) button. Note: Always download the latest stable release (3.12 or 3.13+).

2. Run the Installer:

   • Locate the downloaded .exe file and double-click it.
   • CRITICAL STEP: At the very bottom of the first dialog box, you will see a checkbox labeled "Add Python to PATH". CHECK THIS BOX. This is the most common mistake beginners make.
   • Click "Install Now" (the default installation path is recommended for beginners).

3. UAC Prompt:

   • If a User Account Control (UAC) dialog appears asking for administrator permissions, click "Yes".

4. Verification:

   • Open the Command Prompt (Press Win + R, type cmd, and hit Enter).
   • Type python --version and press Enter.
   • You should see Python 3.12.x (or similar). If you see an error, you likely forgot the PATH step (see Section 9.7 Troubleshooting).

9.2.2 macOS Installation

macOS usually comes with an older version of Python 2.7 pre-installed for system use. Do not uninstall that version, as it is required by macOS itself. We will install a modern Python 3 separately.

Option A: Official Installer (Easiest)

• Download the macOS 64-bit installer from python.org/downloads.
• Run the .pkg file and follow the on-screen instructions.
• This will install Python 3. It also installs the IDLE app and sets up the python3 command in your terminal.

Option B: Homebrew (For developers)

• If you have Homebrew installed, open the Terminal (Applications > Utilities > Terminal) and run:

  brew install python
  

• Homebrew automatically installs the latest Python 3 and pip.

Verification:

• Open Terminal and type:

  python3 --version
  

• The system Python 2 is invoked by python (not python3). Always use python3 and pip3 on macOS.

9.2.3 Linux Installation

Most modern Linux distributions (Ubuntu, Debian, Fedora) come with Python 3 pre-installed. However, you may need to install the full toolchain including pip and venv.

Ubuntu/Debian (APT):

sudo apt update
sudo apt install python3 python3-pip python3-venv

Fedora/RHEL (DNF):

sudo dnf install python3 python3-pip

Arch (Pacman):

sudo pacman -S python python-pip

Verification:

• Open the terminal and run python3 --version. On Linux, like macOS, you must use python3 to invoke Python 3.

9.3 Understanding the PATH Environment Variable

When you type python in the command prompt/terminal, the operating system needs to know where the python.exe (or python3) file is located. It searches through all the directories listed in the PATH environment variable.

• What happens if you don't check "Add Python to PATH": The system cannot find Python, and you get a 'python' is not recognized as an internal or external command error.
• How to fix it manually (if you forgot):
  • Windows: Re-run the installer and select "Modify", check the PATH option, or manually add C:\Users\<YourUsername>\AppData\Local\Programs\Python\Python312\ and C:\Users\<YourUsername>\AppData\Local\Programs\Python\Python312\Scripts\ to the system PATH through System Properties > Environment Variables.
  • macOS/Linux: If you use the official installer, it automatically adds the symlinks. If using a manual source build, you would need to add the /bin directory to your .bashrc or .zshrc.

9.4 Integrated Development Environments (IDEs)

A text editor lets you write code; an IDE (Integrated Development Environment) helps you write, debug, run, and manage it. IDEs provide features like syntax highlighting, auto-completion, debugging tools, and integrated terminals. We will set up three options, but VS Code is highly recommended for this course.

9.4.1 Visual Studio Code (VS Code) – Recommended

1. Download: Go to code.visualstudio.com and download the installer for your OS.
2. Install: Run the installer.
3. Install the Python Extension:
   • Open VS Code.
   • Click the Extensions icon on the left sidebar (or press Ctrl+Shift+X / Cmd+Shift+X).
   • Search for Python (published by Microsoft).
   • Click Install. This extension provides intelligent code completion (IntelliSense), linting, debugging, and testing features.
4. Select the Python Interpreter:
   • Press Ctrl+Shift+P (or Cmd+Shift+P on Mac) to open the Command Palette.
   • Type Python: Select Interpreter.
   • Choose the Python 3 version you just installed. VS Code will usually detect it automatically.
5. Write and Run Code:
   • Create a new file (File > New File).
   • Save it as hello.py.
   • Type print("Hello, World!").
   • Press the green "Run" triangle in the top right, or press Ctrl+F5 (Windows/Linux) / Cmd+F5 (Mac) to run the script. The output will appear in the integrated terminal at the bottom.

9.4.2 PyCharm Community Edition

• Download: Go to jetbrains.com/pycharm/download and download the Community edition (free and open-source).
• Install: Run the installer.
• First Launch:
  • Create a new project. PyCharm automatically creates a virtual environment (see Section 9.6) for each project.
  • Right-click on the project folder, select New > Python File, name it hello.
  • Write your code and click the green "Run" button at the top.

9.4.3 Thonny – For Absolute Beginners

Thonny is incredibly simple and comes bundled with Python, making it the easiest to start with.

• Download: Go to thonny.org and download the installer for your OS.
• Run: Install and open Thonny.
• It automatically opens a simple editor and a shell. Write your code and hit "Run." It shows variables in a separate pane, making it excellent for learning.

9.5 The Integrated Terminal

Regardless of the IDE you choose, you will need to use the terminal/command prompt occasionally.

• VS Code Terminal: View > Terminal or Ctrl+`. It defaults to your system shell.
• Why use it? To run scripts with command-line arguments, install packages, and interact with version control (Git).
• Basic commands to know:
  • cd <folder> – Change directory.
  • dir (Windows) / ls (macOS/Linux) – List files.
  • python hello.py – Run a Python script.

9.6 Package Management with pip

9.6.1 What is pip?

pip stands for "Pip Installs Packages." It is the package installer for Python. You use it to install third-party libraries from PyPI.

• Check if pip is installed: pip --version (Windows) or pip3 --version (macOS/Linux).

• Install a package:

  pip install <package-name>
  

  Example: pip install requests (to handle HTTP requests).

9.6.2 The Problem: Global Packages

If you install all packages globally (pip install numpy), you will eventually run into issues: Project A needs numpy version 1.2, but Project B needs version 1.3. They conflict.

9.6.3 The Solution: Virtual Environments (venv)

A virtual environment is an isolated Python environment for a specific project. It has its own Python interpreter and its own pip directory.

How to create a virtual environment:

1. Open the terminal in your project folder.

2. Run:

   python -m venv myenv
   

   (Replace myenv with your desired environment name, e.g., venv).

3. Activate the environment:

   • Windows: myenv\Scripts\activate
   • macOS/Linux: source myenv/bin/activate

4. Once activated, your terminal prompt will show (myenv). Now, if you run pip install numpy, it installs only into this project folder.

5. Deactivate: deactivate

9.6.4 Managing Dependencies with requirements.txt

To share your project, or to move it to another computer, you need to list all dependencies.

• Generate a list: pip freeze > requirements.txt
• Install from a list: pip install -r requirements.txt

9.7 Troubleshooting Common Installation Issues

9.8 Quizzes

Quiz 1: Installation and PATH

1. What is the most critical step when installing Python on Windows that beginners often forget?

• (A) Selecting the "Customize Installation" option
• (B) Checking "Add Python to PATH"
• (C) Choosing the 32-bit version
• (D) Disabling the firewall

2. On macOS and Linux, which command should you typically use to check if Python 3 is installed?

• (A) python -v
• (B) python3 --version
• (C) python.exe --help
• (D) py --version

3. The PATH environment variable tells the operating system:

• (A) The path to the user's desktop
• (B) The list of directories to search for executable programs
• (C) The location of the hard drive
• (D) The folder where Python scripts are saved

Quiz 2: IDEs and Editors

4. Which of the following is NOT an IDE but rather a code editor that requires extensions to support Python?

• (A) PyCharm
• (B) Thonny
• (C) Visual Studio Code
• (D) IDLE

5. In VS Code, how do you select the Python interpreter for your current project?

• (A) By renaming the file to .interpreter
• (B) By using the Command Palette (Ctrl+Shift+P) and selecting "Python: Select Interpreter"
• (C) By double-clicking the Python icon in the status bar
• (D) It is not possible; only PyCharm allows interpreter selection

6. What makes Thonny a good choice for absolute beginners?

• (A) It only runs on Linux
• (B) It has a very simple interface and shows variable values during step-by-step debugging
• (C) It requires a paid license
• (D) It only works for web development

Quiz 3: Pip and Virtual Environments

7. The standard package manager for Python is called:

• (A) NPM
• (B) PIP
• (C) GEM
• (D) MAVEN

8. What is the primary purpose of a virtual environment (venv)?

• (A) To make the computer run faster
• (B) To isolate project dependencies, preventing version conflicts
• (C) To convert Python code to C++
• (D) To automatically deploy code to a web server

9. Which command activates a virtual environment named my_venv on Windows?

• (A) source my_venv/bin/activate
• (B) my_venv\Scripts\activate
• (C) activate my_venv
• (D) venv start my_venv

10. To generate a list of all installed packages in a project to share with others, you use:

• (A) pip list > packages.txt
• (B) pip freeze > requirements.txt
• (C) pip export requirements.txt
• (D) python -m packages --list

11. If pip is not found on your system, you can still install a package by using:

• (A) python pip install package
• (B) python -m pip install package
• (C) install package
• (D) pip install --fix

9.9 Exercises

Exercise 1: Installation Verification Checklist

Instructions: Perform the following actions on your computer and tick them off. Write down the output for steps that ask for specific information.

• Step 1: Python is installed. Open a terminal/CMD and run python --version (or python3 --version). Write the output here: __________________
• Step 2: pip is installed. Run pip --version (or pip3 --version). Write the output here: __________________
• Step 3: VS Code is installed.
• Step 4: The Python extension is installed in VS Code.
• Step 5: You can select the correct Python interpreter in VS Code (Ctrl+Shift+P > Python: Select Interpreter).

Exercise 2: Hello, World! in the IDE

Instructions:

1. Open your chosen IDE (we recommend VS Code).

2. Create a new folder named unit1-projects on your desktop.

3. Open that folder in VS Code (File > Open Folder).

4. Create a new file named hello.py.

5. Write the following code:

   print("Hello, World!")
   

6. Run the script using the green play button or terminal command.

7. Modify the script to print your name. Example: print("My name is [Your Name]"). Run it again.

8. Submit: Note down any error messages you encountered (if any) and how you resolved them.

Exercise 3: Creating a Virtual Environment and Installing a Package

Instructions:

1. Open a terminal in your unit1-projects folder.

2. Create a virtual environment named venv:

   python -m venv venv
   

   (Note: On Windows, if python doesn't work, use py).

3. Activate the virtual environment:

   • Windows: venv\Scripts\activate
   • macOS/Linux: source venv/bin/activate

4. Verify the prompt changed to (venv).

5. Install a popular package called requests:

   pip install requests
   

6. Run pip freeze. You should see requests and its dependencies listed.

7. Export the list to requirements.txt:

   pip freeze > requirements.txt
   

8. Open requirements.txt and confirm the entries are there.

9. Submit: Copy the output of pip freeze (after installing requests) and paste it into your exercise submission.

Exercise 4: Troubleshooting Practice

Instructions: A friend is trying to run hello.py and gets an error. Read the scenario below and write a one-sentence solution for them.

• Scenario A: Alice types python hello.py in her Windows CMD and gets 'python' is not recognized....

  • Solution: ________________________________

• Scenario B: Bob types pip install numpy in his Linux terminal and gets Permission denied.

  • Solution: ________________________________

• Scenario C: Charlie writes print("Hello) (missing a closing quote) in VS Code. He runs it and gets an error. What kind of error is this?

  • Answer: ________________________________

9.10 Homework Questions

Answer the following questions in complete sentences. Each response should be 3–5 sentences unless otherwise specified.

Short Answer Questions

1. Explain the purpose of the "Add Python to PATH" option during Windows installation. What happens if you do not select it?

2. Why is it recommended to use a virtual environment (venv) for each Python project rather than installing all packages globally?

3. What is the difference between a command-line terminal and a Python IDE like PyCharm? Why might you need both?

Essay Questions

Answer the following questions in 300–400 words each.

4. Imagine you are helping a friend who is completely new to programming install Python on their Windows computer. Write a step-by-step guide that explains not only what to click but why each step is important. Ensure you include how to write their first "Hello, World!" program.

Suggested outline:

• Introduction: Brief welcome and reassurance.
• Step 1: Download from the official Python website (explain avoiding malicious third-party downloads).
• Step 2: Run the installer, and highlight the "Add Python to PATH" checkbox—explain PATH in simple terms.
• Step 3: Click "Install Now" (explain default settings vs. custom).
• Step 4: Verification using CMD (explain what --version does).
• Step 5: Write hello.py (explain why creating a .py file matters).
• Step 6: Run the script from the terminal vs. double-clicking (explain the console window behavior).
• Conclusion: Celebrate the milestone.

5. Describe your experience setting up the Python environment for this course. Which IDE did you choose? What specific challenges did you encounter during installation (e.g., PATH issues, permission errors, choosing the right interpreter), and how did you resolve them? If you had no challenges, explain what you did to ensure a smooth setup and what you would tell a classmate who is struggling.

Suggested outline:

• Introduction: Your chosen OS and IDE.
• Setup Process: Step-by-step recounting.
• Challenges/Resolution: If none, explain preventative measures (e.g., reading the docs carefully).
• Tips for others: A clear list of instructions/advice.
• Conclusion: Current state of your environment (fully functional, ready for the course).

Research Questions

These questions require additional research beyond the tutorial content.

6. Research the concept of "Linting" (e.g., using pylint or flake8 in VS Code). Why is it beneficial to have a linter installed in your IDE? How does it relate to PEP 8 (Python's style guide)?

7. Research the difference between the py launcher (Windows) and the python command. What is the purpose of the py launcher, and how does it simplify managing multiple Python versions on a single machine?

8. Research Jupyter Notebooks (.ipynb). How does a Jupyter Notebook differ from a traditional .py script and IDE? Why might a data scientist prefer a Jupyter Notebook for exploratory analysis? (Hint: Look at interactive cells, markdown support, and visualization integration).

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