Black Jupyter Notebook
I was looking to auto format my notebooks with Black
I found a couple such as
- https://github.com/drillan/jupyter-black
- https://github.com/dnanhkhoa/nb_black
- https://github.com/csurfer/blackcellmagic
- https://github.com/tobinjones/jupyterlab_formatblack
- https://github.com/betatim/joli
However, they were all missing features, were out of date, and had issues.
Writing my own version would have been 2 short files, however, I found that code_prettify is so extensible that you can easily configure it to use Black using the nbextensions configurable parameters.
Features (and issues solved)Permalink
- skip jupyter magic lines
- https://github.com/csurfer/blackcellmagic/issues/5
- https://github.com/drillan/jupyter-black/issues/5
- configurable shortcuts
- adds a toolbar button
- runs for all selected cells
- https://github.com/drillan/jupyter-black/issues/2
- can format whole notebook
- don’t have to run the cells
- don’t have to load ext each notebook
- don’t have to add notebook magics to each cell
- allowing for the cells to be edited while running
- deal with Black’s changing API and works with the most recent Black version, as well as previous ones
- https://github.com/csurfer/blackcellmagic/issues/9
- https://github.com/drillan/jupyter-black/issues/4
- https://github.com/dnanhkhoa/nb_black/issues/2
- works with the most recent jupyter version
- https://github.com/drillan/jupyter-black/issues/6
The python code I’ve written to do the black formatting is:
def black_reformat(cell_text):
import black
import re
cell_text = re.sub("^%", "#%#", cell_text, flags=re.M)
try:
reformated_text = black.format_str(cell_text, 88)
except TypeError:
reformated_text = black.format_str(
cell_text, mode=black.FileMode(line_length=88)
)
return re.sub("^#%#", "%", reformated_text, flags=re.M)
but code_prettify takes a json configuration file that runs javascript so here’s the json you need to paste into the configuration window:
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| { | |
| "python": { | |
| "library": "import json\ndef black_reformat(cell_text):\n import black\n import re\n cell_text = re.sub('^%', '#%#', cell_text, flags=re.M)\n try:\n reformated_text = black.format_str(cell_text, 88)\n except TypeError:\n reformated_text = black.format_str(cell_text, mode=black.FileMode(line_length=88))\n return re.sub('^#%#', '%', reformated_text, flags=re.M)", | |
| "prefix": "print(json.dumps(black_reformat(u", | |
| "postfix": ")))" | |
| }, | |
| "r": { | |
| "library": "library(formatR)\nlibrary(jsonlite)", | |
| "prefix": "cat(toJSON(paste(tidy_source(text=", | |
| "postfix": ", output=FALSE)[['text.tidy']], collapse='\n')))" | |
| }, | |
| "javascript": { | |
| "library": "jsbeautify = require('js-beautify')", | |
| "prefix": "console.log(JSON.stringify(jsbeautify.js_beautify(", | |
| "postfix": ")));" | |
| } | |
| } |
To installPermalink
- go to your Nbextensions in your jupyter notebook
- to install nbextensions see https://github.com/ipython-contrib/jupyter_contrib_nbextensions#1-install-the-python-package
- enable Code prettify
- paste above json into text box labeled
json defining library calls required to load the kernel-specific prettifying modules, and the prefix & postfix for the json-format string required to make the prettifying call.
This also requires black to be installed in the running kernel and it therefore goes without saying this only works in py>=3.6