Reticulate does not play nice with Rich progressbars

Dear Reticulate team

Problem description

How could we get reticulate to play nicely with the progress bars from Rich, please? Right now, when calling Rich progress bars in a R notebook:

either, when output capture is not enabled, the notebook does not display the bars at all until they are finished. Not ideal for a progress bar :)
or, when output capture is enabled with the RETICULATE_REMAP_OUTPUT_STREAMS=1 environment variable, it completely messes their formatting, see below.

Reminder, for ease of finding the source, that Reticulate remaps the outputs here: https://github.com/rstudio/reticulate/blob/740169ae2a7c943115b2a4eca3b5a0b7d9e5ef3a/inst/python/rpytools/output.py#L130 which is called here: https://github.com/rstudio/reticulate/blob/740169ae2a7c943115b2a4eca3b5a0b7d9e5ef3a/R/output.R#L1

Setup for reproduction

The below steps are with R stack:

R 4.4.1
Reticulate 1.38

Python stack:

Python 3.12
rich 13.7.1

OS:

Tested with macOS Sonoma 14.5 with Rstudio 2024.04.1+748
And with Windows Server 2022 Datacenter with Rstudio 2024.04.2 Build 764. In that latter one, the single progress bar works fine, but still not the multi-tasks.

In my .Renviron:

RETICULATE_REMAP_OUTPUT_STREAMS=1

And the very first R cell in my R notebook to install the packages needed:

library(reticulate)
CENV="test_rich"

if(!condaenv_exists(CENV)) {
  conda_create(CENV, python_version="3.12")
  conda_install(CENV, c("rich"))
}
use_condaenv(CENV)

Single progress bar (mac only)

First problem on single progress bars: the output of the beginning of line is cut, missing the first 6 characters.

import time
from rich.progress import track

for i in track(range(20), description="Processing..."):
  time.sleep(.1)  # Simulate work being done

Note the letters "Process" are missing at the beginning of the lines. Only "sing" is showing.

Multiple progress bars (both mac and Windows)

Now let's try with multiple parallel bars, and observe that, instead of updating each line, a new line is shown at each update.

import time

from rich.progress import Progress

with Progress() as progress:

    task1 = progress.add_task("[red]Downloading...", total=1000)
    task2 = progress.add_task("[green]Processing...", total=1000)
    task3 = progress.add_task("[cyan]Cooking...", total=1000)

    while not progress.finished:
        progress.update(task1, advance=0.5)
        progress.update(task2, advance=0.3)
        progress.update(task3, advance=0.9)
        time.sleep(0.002)

The behaviour is exactly the same whether the python code is itself in a python chunk, or sourced from a python file by executing

reticulate::source_python("test_rich.py")

where test_rich.py is the python code listed above.

Expected behaviour

The expected behaviour is that obtained by running python test_rich.py, which shows the progress bar each on its line and updates them each on their own line:

Use case

This bug is quite problematic when using Pymc in reticulate. Pymc relies on Rich progressbars since https://github.com/pymc-devs/pymc/pull/7233 . Those are long-running time bars (thus quite needed), and with many many steps thus which making massive outputs (either in console or in-line) and progressively slowing down Rstudio to a crawl.

Thanks a lot for any help!

rstudio / reticulate