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Virtual Environments: Isolating Project Dependencies

Isolate each project's dependencies.

1. Why Isolate Dependencies

  • Two projects can need different versions of the same package (pandas 1.5 vs 2.1)
  • Installing everything globally means one upgrade can break an unrelated project
  • A virtual environment gives each project its own private set of installed packages

2. Official Docs: venv

"Creates lightweight virtual environments, each with their own independent set of Python packages installed in their site directories"

Added in Python 3.3 · recommended tool since 3.5.

venv docs

python -m venv /path/to/new/virtual/environment

docs.python.org/3/library/venv.html

3. Pick a Tool

  • venv — built into Python, no install needed
  • conda / mamba — manages Python itself plus packages
  • poetry / uv — modern dependency + packaging managers
  • CCDS asks which one you want when it scaffolds a project (see Cookiecutter Data Science)

4. Typical Workflow

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