Quarto fails to recognize Python virtual environment

[aronvandepol]

Description

I have recently switched to astral UV to manage python for me. I have tried to make it work nicely with Quarto and setup a testing script to do this. I create a virtual env with UV that my quarto project will use. this is located at .venv dir next to the quarto qmd file.

I manually install jupyter using uv pip install jupyter to ensure the venv can work with quarto.

I have tried the following configs to make quarto pick this up:

1. (Set executable)

---
title: "Testing UV with Quarto"
execute:
  python: ".venv/bin/python"
  external: true

---

## Testing Pandas with UV

```{python} 
#| echo: false
#| code-fold: true
!uv pip install pandas torch
```


```{python}
import pandas as pd

# Create a sample DataFrame
data = pd.DataFrame({
    "Name": ["Alice", "Bob", "Charlie", "David"],
    "Age": [24, 27, 22, 32],
    "City": ["New York", "Los Angeles", "Chicago", "Houston"]
})

# Display the DataFrame
print("Sample DataFrame:")
print(data)
```

```{python} 
import torch
x = torch.rand(3,3)
print(x)
```

quarto render results in a 'There is an unactivated Python environment in .venv. Did you forget to activate it?' error. Alongside the fact that the packages weren't installed.

I then adjusted the _quarto.yml

project:
  type: website
  pre-render:
  - "./set.sh"

this calls the prerender script:

export QUARTO_PYTHON=.venv/bin/python

calling quarto render with this still results in it not using the environment.

I then came across the _environtment file which i tried to setup.

_environment

QUARTO_PYTHON=.venv/bin/python

Again, we get the same error that the python venv is not being used.

When in my terminal I source the venv directly using source ./venv/bin/activate and run quarto render still the same error occurs.

Only when i call" export QUARTO_PYTHON=.venv/bin/python directly before running quarto render will the test file run. The necessary packages get installed first through !uv pip install pandas torch and the code and renders into a html file without errors.

My question is if there is a different way, preferably through Quarto, either the project _quarto.yml or the _environment file to set this? Perhaps I am doing something wrong? The idea is that I don't have to call export QUARTO_PYTHON=.venv/bin/python in my terminal everytime before rendering.

Any help is appreciated!