Feature request: Support for formatting the python code in jupyter notebooks

[MrinalJain17]

Jupyter notebooks are quite popular and are used a lot (especially in tasks related to data analysis, visualization etc.).
These notebooks are also used as presentations and tutorials.
It would be great if black could format the code within the cells of the notebooks.

[jgirardet]

https://github.com/csurfer/blackcellmagic

[MrinalJain17]

This is great.. Thanks!

[cdeil]

Is there something like

$ black-notebook analysis.ipynb

that runs black on all code cells in the notebook(s) from the command line and saves them back in-place?

I guess it's just ~ 10 lines using the Jupyter API, but I'd still prefer using it over writing it if someone has written that already.

[srstevenson]

@cdeil and others interested in being able to format notebooks from the command line: mcflugen/nbblack is a fairly new project that looks to offer that.

[KwatMDPhD]

https://github.com/KwatME/clean_ipynb will do.

[MarvinT]

It's pretty easy to configure the code-prettify Nbextension to use Black. Heres the configuration I use and some install instructions.

https://gist.github.com/MarvinT/a072aa992e977496974aaf492287b08c
and
https://marvint.github.io/Black-Jupyter/

[MarcoGorelli]

Is there something like

$ black-notebook analysis.ipynb

that runs black on all code cells in the notebook(s) from the command line and saves them back in-place?

I guess it's just ~ 10 lines using the Jupyter API, but I'd still prefer using it over writing it if someone has written that already.

@cdeil you can do this with nbQA https://github.com/nbQA-dev/nbQA

e.g. from the command line:

nbqa black notebook.ipynb --nbqa-mutate

e.g. as pre-commit hook:

repos:
- repo: https://github.com/nbQA-dev/nbQA
  rev: 0.13.1
  hooks:
  - id: nbqa-black
    args: [--nbqa-mutate]

Disclaimer: I'm the author of nbQA

---

As of 21.8b0, black itself now does this!

[KwatMDPhD]

Try this https://github.com/KwatME/clean_ipynb

[SamuelMarks]

It's now builtin, just pip install black[jupyter]

[KwatMDPhD]

For julia https://github.com/KwatMDPhD/Clean.jl

[cdeil]

Thank you very much!

It wasn't obvious to me at first from the README what this does.

It looks like what you implemented is the command line part so that black spam.ipynb formats the notebook.

The other workflow of doing the formatting from within the Jupyter IDE isn't built-in yet in black or jupyter lab yet, for that some third-party plugin should be used, right?

I see pre-commit support was also added:
https://black.readthedocs.io/en/stable/integrations/source_version_control.html

Nice!

[MarcoGorelli]

The other workflow of doing the formatting from within the Jupyter IDE isn't built-in yet in black or jupyter lab yet, for that some third-party plugin should be used, right?

Some third-party plugins do exist, but most don't use black's Jupyter API.

One that does, which IMO deserves more attention, is @n8henrie 's https://github.com/n8henrie/jupyter-black