How to set up a virtual environment for Python

This blog post is a small cheat sheet on setting up a virtual environment for Python venv.

Note: The virtual environment installation.

python3 -m pip install virtualenv --user 

Step 1: Create a virtual environment

python3.11 -m venv my-env-3.11

When you look into your current folder, you will notice that the execution of this command created a new folder called my-env-3.11.

my-env-3.11
|-bin
|-include
|-lib
pyvenv.cfg

Step 2: Activate the environment

source ./my-env-3.11/bin/activate

Step 3: Install your project-related requirements

python3 -m pip install -r requirements.txt

Step 3: Deactivate the virtual environment

deactivate

In addition:

Show your current virtual Python environment.

virtualenv --version

Verify and manage your Python versions with pyenv. (blog post “intro to pyenv”)

#install or update
brew update
brew upgrade pyenv
#system
which python
#pyenv
pyenv versions
pyenv -v
pyenv install --list
pyenv install -v 3.11.2
#optional: export PYENV_VERSION=3.11.2
pyenv global 3.11.2
pyenv versions

I hope this was useful to you, and let’s see what’s next?

Greetings,

Thomas

#python, #venv, #cheatsheet

In this context it can be useful to know this:

• Problem: error: externally-managed-environment

error: externally-managed-environment

× This environment is externally managed
╰─> To install Python packages system-wide, try brew install
    xyz, where xyz is the package you are trying to
    install.

• Solution 1(Linux): Remove `EXTERNALLY-MANAGED`

rm /opt/homebrew/Cellar/python@3.12/3.12.3/EXTERNALLY-MANAGED

• Solution 2 (macOS): Use the –break-system-packages option

python3 -m pip install pandas --break-system-packages

• Solution 3: Using pipx

brew install pipx
sudo pipx ensurepath