Polars plugins should be referenced by .venv relative path

[mat-ej]

Checks

• I have checked that this issue has not already been reported.
• I have confirmed this bug exists on the latest version of Polars.

Reproducible example

Hi Polars team and community, thanks in advance for your advice.

pls see below screenshot output of the show_graph(),

Example using polars-ds:

import polars as pl
import polars_ds as pds

pds.lin_reg(
        pl.col("x1"), pl.col("x2"),
        target = [pl.col("y"), pl.col("y2")],
        add_bias=False
).meta.show_graph()

Log output

Issue description

when using custom polars plugins inside Pl.Expr expression, the node uses absolute system path to point to a rust lib to do the operation. (This causes confusing behaviour when serializing such expressions)

Expected behavior

It would be a lot more practical if when serializing pl.Expr graph, such node pointed to a relative path to .venv instead of absolute path. I believe this would make the code portable from one .venv to another if the versions match. (Correct me If I m wrong)

Installed versions

polars: 1.22.0
polars-ds: 0.8.2

[ritchie46]

Yes, that's also something we discussed internally to make it work for Polars cloud. This can be resolved completely in Python.

Any help here would be appreciated.

[anath2]

Hi, I would like to work on this issue

[mat-ej]

Feel free to take it, I am still trying to allocate time for going through polars code.