ipynb_drop_output.py

#!/usr/bin/env python

"""
Suppress output and prompt numbers in git version control.

This script will tell git to ignore prompt numbers and cell output
when looking at ipynb files if their metadata contains:

    "git" : { "suppress_output" : true }

The notebooks themselves are not changed.

See also this blogpost: http://pascalbugnion.net/blog/ipython-notebooks-and-git.html.

Usage instructions
==================

1. Put this script in a directory that is on the system's path.
   For future reference, I will assume you saved it in
   `~/bin/ipynb_drop_output`.
2. Make sure it is executable by typing the command
   `chmod +x ~/bin/ipynb_drop_output`.
3. Configure a filter in your ~/.gitconfig using these
   git commands:

   git config --global filter.clean_ipynb.clean ipynb_drop_output
   git config --global filter.clean_ipynb.smudge cat
4. Configure this filter for jupyter notebooks in your project's
   ~/.gitattributes by adding:

    *.ipynb    filter=clean_ipynb

To tell git to ignore the output and prompts for a notebook,
open the notebook's metadata (Edit > Edit Notebook Metadata). A
panel should open containing a dictionary with some metadata.

Add an extra entry

        "git" : { "suppress_outputs" : true }

and save your notebook.

Notes
=====

Script modified from https://gist.github.com/pbugnion/ea2797393033b54674af

This script is inspired by http://stackoverflow.com/a/20844506/827862, but
lets the user specify whether the ouptut of a notebook should be suppressed
in the notebook's metadata, and works for IPython v3.0.
"""

import sys
import json

nb = sys.stdin.read()

json_in = json.loads(nb)
nb_metadata = json_in["metadata"]
suppress_output = False
if "git" in nb_metadata:
    if "suppress_outputs" in nb_metadata["git"] and nb_metadata["git"]["suppress_outputs"]:
        suppress_output = True
if not suppress_output:
    sys.stdout.write(nb)
    exit()


ipy_version = int(json_in["nbformat"])-1 # nbformat is 1 more than actual version.

def strip_output_from_cell(cell):
    if "outputs" in cell:
        cell["outputs"] = []
    if "prompt_number" in cell:
        del cell["prompt_number"]
    if "execution_count" in cell:
        cell["execution_count"] = None


if ipy_version == 2:
    for sheet in json_in["worksheets"]:
        for cell in sheet["cells"]:
            strip_output_from_cell(cell)
else:
    for cell in json_in["cells"]:
        strip_output_from_cell(cell)

json.dump(json_in, sys.stdout, sort_keys=True, indent=1, separators=(",",": "), ensure_ascii=False)
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