Manage Python Virtual Environments With venv

Create a virtual environment
Activate the environment
Install packages into the environment
Save dependencies to a requirements file
Recreate the environment from requirements
Deactivate the environment
Remove and rebuild the environment
Notes

Python virtual environments isolate project dependencies so one project does not overwrite or conflict with another. The built-in venv module is the standard way to manage that isolation in many local development workflows.

Create a virtual environment

python -m venv .venv

This creates a .venv directory containing:

a Python interpreter for the environment
installed packages for that environment
activation scripts for different shells

Activate the environment

PowerShell

.venv\Scripts\Activate.ps1

Command Prompt

.venv\Scripts\activate.bat

macOS or Linux

source .venv/bin/activate

After activation, python and pip point to the environment instead of the system interpreter.

Install packages into the environment

python -m pip install snowflake-connector-python pandas

Using python -m pip helps ensure that pip installs into the currently active interpreter.

Save dependencies to a requirements file

python -m pip freeze > requirements.txt

This captures the installed package versions so the environment can be recreated later.

Recreate the environment from requirements

python -m venv .venv
source .venv/bin/activate
python -m pip install -r requirements.txt

On Windows, the activation command should match the shell in use.

Deactivate the environment

deactivate

This returns the shell to the default system Python.

Remove and rebuild the environment

If an environment becomes inconsistent, it can be removed and recreated.

rm -rf .venv
python -m venv .venv
python -m pip install -r requirements.txt

On Windows PowerShell:

Remove-Item -Recurse -Force .venv
python -m venv .venv
python -m pip install -r requirements.txt

Notes

keep .venv out of version control
store dependency definitions in requirements.txt or another lock file
activate the environment before running scripts, tests, or package installs
recreate the environment when package state becomes difficult to debug