Version: Dec 21, 2024

Python Basics

Overview

Times keep changing for the tools we use. Since so many solutions are relaying on Python, Python has gotten to the point where it needs to be isolated so packages don't negatively impact each other.

This guide hopes to help those who run into issues with Python. Please note this guide is from the perspective of MacOS Sequoia.

Checking Python Version

• For Python under 3 or python 3, respectively. bash python --version python3 --version

Locate Python

• Find the exact locations of the Python executables: bash which python which python3
• List Python Installed via Homebrew bash brew list | grep python
• You can check the version via pyenv bash brew install pyenv pyenv versions

Installing Python

Check Home Brew

• Homnebrew is a good choice as package manager. Its good practice to update Homebrew is you have'nt done so. bash brew --version brew update
• Then to install Python bash brew install python

Updating PATH

• Use the correct Python version. Homebrew installs Python in /usr/local/bin (Intel Macs) or /opt/homebrew/bin (M1/M2 Macs). Ensure that this version is prioritized in your PATH.
• Add the following to your ~/.zshrc or ~/.bashrc (depending on your shell): bash export PATH="/usr/local/bin:$PATH" # For Intel Macs export PATH="/opt/homebrew/bin:$PATH" # For M1/M2 Macs
• Reload your shell: bash source ~/.zshrc

Install a Specific Version of Python

• If you need a specific version of Python, you can use Homebrew’s python@x formula. For example:
• Install Python 3.10: bash brew install python@3.10
• To use a specific version, link it to your default python3 command: bash brew link --overwrite python@3.10

Setting up a Virtual Environment

• This one was new to me, I need to know setup virtual environments to download packages and develop!

1. Prerequisites

• Ensure you have Python installed. Verify the version: bash python3 --version

2. Create a Virtual Environment

• Navigate to Your Project Directory: bash cd /path/to/your/project

• Use Python’s built-in venv module to create the environment: bash python3 -m venv venv_name

• Replace venv_name with the desired name for the virtual environment (e.g., venv or env).

• This creates a directory named venv_name containing the virtual environment.

3. Activate the Virtual Environment

• macOS/Linux: bash source venv_name/bin/activate

• Windows: bash venv_name\Scripts\activate

• Once activated, you’ll see the environment name in your shell prompt, indicating that the virtual environment is active, e.g.: bash (venv_name) user@computer:~/project$

• To exit the virtual environment: bash deactivate

4. Install Packages

• This will install packages locally to the virtual environment only, which is the point of it.
• Once you deactivate, the packages are no longer reachable, but they are still there in the project directory.
• Inside the virtual environment, you can use pip to install packages: bash pip install package_name

• Example: bash pip install numpy

• List current packages: bash pip list

5. Re-Activate the Environment

• If you need to work on the project again, re-activate the virtual environment: bash source venv_name/bin/activate # macOS/Linux venv_name\Scripts\activate # Windows

6. Save and Reuse Dependencies

• To share your environment with others or recreate it via export installed packages: bash pip freeze > requirements.txt

• Reinstall Dependencies in a New Environment: bash pip install -r requirements.txt

• Delete a Virtual Environment bash rm -rf venv_name

7. Using Virtual Environments with IDEs

• Most modern IDEs (like VSCode or PyCharm) detect and integrate with virtual environments automatically.
• VSCode:
  • Install the Python extension.
  • Open the Command Palette (Ctrl+Shift+P or Cmd+Shift+P)
  • Select “Python: Select Interpreter” and choose the virtual environment.
• PyCharm:
  • Go to “Settings” → “Project Interpreter.”
  • Add your virtual environment as a new interpreter.

By using virtual environments, you can keep your Python projects organized and avoid dependency conflicts. Cheers!