Source code for ipynbcompress.ipynbcompress

# coding: utf-8
from base64 import b64decode, b64encode
from PIL import Image
from io import BytesIO
from os import stat
from IPython.nbformat import read, write

[docs]def compress(filename, output_filename=None, img_width=2048, img_format='png'): """Compress images in IPython notebooks. Parameters ---------- filename : string Notebook to compress. Will take any notebook format. output_filename : string If you do not want to overwrite your existing notebook, supply an filename for the new compressed notebook. img_width : int Which width images should be resized to. img_format : string Which compression to use on the images, valid options are *png* and *jpeg* (**requires libjpeg**). Returns ------- int Size of new notebook in bytes. """ orig_filesize = stat(filename).st_size # compress images nb = read(filename, as_version=4) outputs = [cell.get('outputs', []) for cell in nb['cells']] # omit empty outputs outputs = [o for o in outputs if len(o)] # flatten outputs = [o for lines in outputs for o in lines] for output in outputs: data = output.get('data', {}) if not data: continue keys = data.keys() for key in keys: if 'image' in key: string = ''.join(data[key]) bytes_img = b64decode(string) io_img = BytesIO(bytes_img) img = factor = float(img_width) / img.size[0] if factor < 1: # only resize large images new_size = [int(s*factor+0.5) for s in img.size] img = img.resize(new_size) out = BytesIO(), img_format) mime = 'image/' + img_format del data[key] data[mime] = b64encode('ascii') # save notebook if not output_filename: output_filename = filename try: output_format = nb.metadata.orig_nbformat except AttributeError: output_format = 4 write(nb, output_filename, version=output_format) # calculate bytes saved bytes_saved = orig_filesize - stat(output_filename).st_size if bytes_saved <= 0: print('%s: warning: no compression - %s bytes gained' % (filename, -bytes_saved)) return bytes_saved