Possible to set root_prefix from config file?

[matthewfeickert]

Hi. 👋 Thanks for making jupytext. In the docs it notes that format spec takes the form of

jupytext/docs/config.md

Lines 9 to 16 in b7a8dac

	You can pair a notebook to as many text representations as you want (see our _World population_ notebook in the demo folder). Format specifications are of the form
	```
	[[root_folder//][path/][prefix]/][suffix.]ext[:format_name]
	```
	where
	- `ext` is one of `ipynb`, `md`, `Rmd`, `jl`, `py`, `R`, `sh`, `cpp`, `q`. Use the `auto` extension to have the script extension chosen according to the Jupyter kernel.
	- `format_name` (optional) is either `light` (default for scripts), `nomarker`, `percent`, `hydrogen`, `sphinx` (Python only), `spin` (R only) — see the [format specifications](formats.md).
	- `root_folder`, `path`, `prefix` and `suffix` allow to save the text representation to files with different names, or in different folders (see the [configuration files examples](config.md#Configuring-paired-notebooks-globally)).

and later shows how to specify filtering on specific subdirectories

jupytext/docs/config.md

Lines 83 to 97 in b7a8dac

	You can pair notebooks in trees with a `root_prefix` separated with three slashes, e.g.
	```
	# Pair notebooks in subfolders of 'notebooks' to scripts in subfolders of 'scripts'
	formats = "notebooks///ipynb,scripts///py:percent"
	```
	or alternatively, using a dict to map the prefix path to the format name:
	```
	# Pair notebooks in subfolders of 'notebooks' to scripts in subfolders of 'scripts'
	[formats]
	"notebooks/" = "ipynb"
	"scripts/" = "py:percent"
	```
	Note that if you are using a `pyproject.toml` file with this dict format, you should make sure the table header is instead `[tool.jupytext.formats]`.
	The `root_prefix` is matched with the top-most parent folder of the matching name, not above the Jupytext configuration file.

This means that if I wanted to have a pyproject.toml config that would only pair notebooks to py:percent files in a directory named examples/ that I could write it as such:

[tool.jupytext]
# Always pair ipynb notebooks in examples/ directory to py:percent files
formats = ["examples///ipynb", "examples///py:percent"]

Is it currently possible to specify in the config file a root_prefix option that would allow for keeping a more (in my very subjective view) readable format like the following (which is invalid)

# THIS IS INVALID
[tool.jupytext]
root_prefix = "examples/"
# Always pair ipynb notebooks in examples/ directory to py:percent files
formats = ["ipynb", "py:percent"]

If so, can you tell me how to write it correctly?

[mwouts]

Hello @matthewfeickert , thanks for your question! Unfortunately at the moment there is no such root_prefix option in the [tool:jupytext] section of pyproject.toml files.

Does the example you gave above works? Alternatively you might use a jupytext.toml file in the examples directory (with content formats="ipynb,py:percent") to achieve the pairing just in that directory.

[matthewfeickert]

Thanks for the reply, @mwouts! This is helpful — I just wanted to make sure I wasn't missing something.

Does the example you gave above works? Alternatively you might use a jupytext.toml file in the examples directory (with content formats="ipynb,py:percent") to achieve the pairing just in that directory.

Yup the working examples are viable, and I like the idea about using per directory config files. Thanks!

I'm going to close this Issue as I don't think there are any changes that are planned that might affect this in the near future.