Quarto uses wrong Python version?

[kellertuer]

I installed quarto last week on two machines and it was working great.
I want to use it with Julia, so I also installed IJulia and Conda and quarto rendered things just fine.

Now it still works on one machine but not on the other and I can not figure out what changed nor what is different.

When I now call

❯ quarto render Optimize\!.qmd

Starting julia-1.6 kernel...ERROR: 

[Errno 2] No such file or directory: '/Applications/Julia-1.6.app/Contents/Resources/julia/bin/Julia'

which is ok in the sense as that Julia version I deleted in November when I switched to juliaup – but how did quarto (and only on one machine) switch to using a different Julia? Or is it maybe using a different Python?
My usual Problem with Python is, that I feel I have far too many Python versions and I never know which version is used where, so any tips in that direction are also welcome.

I have an Apple M1, so my usual Julia I would like to use (and do use on one machine) is the juliaup one – and Python installed via Conda.jl

Any help how to narrow this down appreciated, since I really do not know how quarto switched to trying to use a version that I removed 3 months ago.

[kellertuer]

...now I removed said Kernel, then it runs only with Python since there is no Julia left and the (Julia) code in the .qmd does not get executed. So It really seems to be the wrong python. But how to tell quarto the right one? I now read through the docs for half an hour but it seems the docs assume, that that all just works?

So if it works its great – if not (due to more than one Python version probably) – I could not find anything yet.

[cderv]

Can you run quarto check jupyter in the same environment you are using quarto render ?

This should tell you which Python version is seen and used.

Doc about selection is here : https://quarto.org/docs/computations/python.html#installation.
From this doc:

Quarto will select a version of Python using the Python Launcher on Windows or system PATH on MacOS and Linux.

So your python found in PATH should be used ? What is on your PATH ? What does which python3 returns ?
Using any tooling that put Python on PATH for a project would work with Quarto I believe.

You can override the version of Python used by Quarto by setting the QUARTO_PYTHON environment variable.

You can always use this environment variable in a project to force Quarto to use a specific version for a project or for your system.

Hope it helps narrow your configuration and what Quarto sees. Also updating Quarto can help in some situation as we fix issues over time.

[kellertuer]

I basically removed quarto and IJulia and installed both again, that helped. My path is crowded, since most things I installed add something. I might have to clean that at some point as well. For now the reinstall and setting the QUARTO_PATH resolved the problem.

[mcaruel]

Hello,
What is the procedure to change the QUARTO_PYTHON environment variable? I want Quarto to use a specific conda environment not located in the directory of the .qmd document to render.

[delapazruiz]

Hello @cderv

Could you provide a file example that defines a Python or R version?
I am reading the following link, but I'm not familiar with those configurations, and I can not make it work:
https://quarto.org/docs/projects/environment

What file type is the '_environment' mentioned in the above link? Should I write it as a .txt file?
If I want to define an r version, is it correct to type the following in the _environment file?

QUARTO_R

R_VERSION=4.0.3

I appreciate any help you can provide.

[mcanouil]

_environment is the name of the file which is a plain text file in which you can set QUARTO_R=/opt/R/4.2.3/bin, etc.

[delapazruiz]

@mcanouil, Thank you.

After creating a quarto project with an renv, I got the renv.lock file. In this file, I found the following code lines:

"R": {
"Version": "4.3.1",
"Repositories": [
{
"Name": "CRAN",
"URL": "https://packagemanager.posit.co/cran/latest"
}
]
},
"Python": {
"Version": "3.9.15",
"Type": "virtualenv",
"Name": "./renv/python/virtualenvs/renv-python-3.9"
},

I suppose that using renv is also a solution to define my preferred Python and R versions, right?

[mcanouil]

What does renv has to do with setting R/Python for Quarto?
renv does not set anything, it only records versions as documented on the tool website (https://rstudio.github.io/renv/index.html).

[delapazruiz]

The first time, when creating a new quarto project and adding the renv option in Rstudio, I got the option to set the R version. It only happens once. Further versions are kept as you choose the first time.

Thank you. I was finally able to define any R version that I wanted. In the _environment file, I typed the following line (for Windows 11):
QUARTO_R="C:\Program Files\R\R-4.3.0\bin"

To confirm that the quarto project was using the version of my choice, I rendered the following .qmd:

---

title: "testRpyversion"

R.version.string

import platform
print(platform.python_version())

Based on this discussion: #6162 I realized that only rendered .qmd files confirm whether your quarto project is using the R/Python version of your choice. Running cell chucks only gives you the versions used by the system, not your quarto project.