Description

py2nb is a python package for converting python scripts with minimal markdown to jupyter notebooks.

Markdown cells are rendered from comments beginning with #|, splits between code cells are created by comment lines beginning with #-, and command cells (for shell commands like pip installs) are created from comments beginning with #!

nb2py converts from jupyter notebooks to python

Installation

Users can install using pip:

pip install py2nb

from source:

git clone https://github.com/williamjameshandley/py2nb
cd py2nb
python setup.py install

or for those on Arch linux it is available on the AUR

Programmatic Usage

Both py2nb and nb2py can be imported and used programmatically:

import py2nb
import nb2py

# Convert script to notebook
notebook_path = py2nb.convert('script.py')

# Convert with custom output and execution
executed_notebook = py2nb.convert('script.py',
                                  output_name='workshop.ipynb',
                                  execute=True)

# Convert notebook back to script
script_path = nb2py.convert('notebook.ipynb', output_name='converted.py')

Example

If one has a script named example.py containing the code:

#| # Testing ipython notebook
#| This is designed to demonstrate a simple script that converts a script into
#| a jupyter notebook with a simple additional markdown format.
#|
#| Code by default will be put into code cells
#|
#| * To make a markdown cell, prefix the comment line with '#|' or '# |'
#| * To split a code cell, add a line beginning with '#-' or '# -'
#| * To make a command cell, prefix the comment line with '#!' or '# !'

#! pip install matplotlib numpy
#! pip install scipy

import matplotlib.pyplot as plt
import numpy as np

%matplotlib inline

#| Here is a markdown cell.
#| Maths is also possible: $A=B$
#|
#| There are code cells below, split by `'#-'`:

# | Here is another markdown cell

x = np.random.rand(5)

#-------------------------------

y = np.random.rand(4)
z = np.random.rand(3)

#| Here are some plots

x = np.linspace(-2,2,1000)
y = x**3
fig, ax = plt.subplots()
ax.plot(x,y)

# -------------------------------

# | Here is another plot

x = np.linspace(-np.pi, np.pi, 201)
fig, ax = plt.subplots()
ax.plot(x,np.sin(x))

then running

py2nb example.py

produces the notebook example.ipynb

To see an executed version with outputs and plots, run:

py2nb example.py --execute --output example_executed

which produces example_executed.ipynb with all code cells executed and outputs displayed.

Command Line Options

py2nb script.py                      # Basic conversion
py2nb script.py --no-validate        # Skip notebook validation
py2nb script.py --execute            # Convert and execute notebook
py2nb script.py --output workshop    # Custom output name
py2nb script.py --output workshop --execute  # Custom name + execution

nb2py notebook.ipynb                 # Convert notebook to script
nb2py notebook.ipynb --output script # Custom output script name

Command Blocks

Command blocks allow you to run shell commands (like pip installs) in separate notebook cells:

#| # Workshop Example
#| This demonstrates command blocks for dependency management

#! pip install numpy matplotlib
#! pip install seaborn

import numpy as np
import matplotlib.pyplot as plt

#| ## Advanced Analysis
#| Install additional dependencies when needed

#! pip install scikit-learn

from sklearn import datasets

This creates dedicated cells for commands, improving modularity and compatibility with platforms like Google Colab.

Execution Option

The --execute option runs the converted notebook using jupyter nbconvert, creating a new notebook with outputs included:

py2nb workshop.py --execute                    # Execute in place
py2nb workshop.py --output clean               # Create clean.ipynb
py2nb workshop.py --output executed --execute  # Create executed.ipynb with outputs

The --output option allows you to specify custom filenames, giving you complete control over the generated notebook names. Useful for creating workshop materials with pre-computed results, or for testing that your workshop notebooks execute successfully.

Requirements: Requires nbconvert to be installed (pip install nbconvert).

Testing

To run the test suite:

python test_py2nb.py

The test suite includes 16 test cases covering:

• Basic conversion functionality

• Markdown cell creation (#| syntax)

• Code cell splitting (#- syntax)

• Command block creation (#! syntax)

• Notebook execution (--execute option)

• Custom output filenames (--output option)

• nb2py reverse conversion with custom output

• Programmatic module usage

• Mixed syntax combinations

• Notebook metadata and validation

• UTF-8 encoding support

• Backward compatibility

• Error handling

Vim Integration

For vim users working with py2nb syntax, you can enhance your editing experience:

Syntax Highlighting

Add to your .vimrc for basic py2nb syntax support:

" py2nb syntax highlighting
autocmd BufRead,BufNewFile *.py syntax match Comment "#|.*$"
autocmd BufRead,BufNewFile *.py syntax match Special "#!.*$"
autocmd BufRead,BufNewFile *.py syntax match Delimiter "#-.*$"

File Templates

Create a py2nb template in ~/.vim/templates/py2nb.py:

#| # Workshop Title
#|
#| Brief description and learning objectives

#! pip install required_packages

import standard_libraries

#| ## Section 1: Core Concepts
#| Essential material description

# Your code here

#-

# Next code cell

#| ## Section 2: Advanced Topics
#| Building on previous concepts

Then use :read ~/.vim/templates/py2nb.py to insert the template.