Colaboratoryで画像を参照する

Deep Learning (ud730) - らんだむな記憶なんだけど、.ipynb を突っ込んだ場合に img src での画像参照がインラインで表示されない。

• python - How to display an image within the notebook in Google Colab (like in Anacondan Jupyter Notebook)? - Stack Overflow
• html - How can I open images in a Google Colaboratory notebook cell from uploaded png files? - Stack Overflow
• How to insert an inline image in Google Colaboratory markdown call from local path - Stack Overflow

のようにすれば良いらしいので・・・

import os, sys, subprocess, glob, shutil
from google.colab import drive 
drive.mount('/content/drive')

img_dir = "/content/drive/My Drive/PATH/TO/IMG_DIR"
shutil.copytree(img_dir, "/usr/local/share/jupyter/nbextensions/")

みたいな感じにコードを実行させてGoogle drive上の画像データをColabのコンテナにコピーして使う。
.ipynb は以下のようなコードで画像の参照パスを予め変更しておく。jsonを真面目にパースして分割するのは面倒臭いので正規表現で逃げる・・・。

#! /usr/bin/env python
# -*- coding: utf-8 -*-

import os, sys, re

def insert_code_cell_between_markdowns(lines, line, prefix=""):
    lines[-1] = re.sub(r"\s*,\s*$", "", lines[-1])

    lines.append(f'   ]\n  }},\n  {{\n   "cell_type": "code",\n   "metadata": {{}},\n   "source": [{prefix}')
    lines.append(line)
    lines.append('   ]\n  },\n  {\n   "cell_type": "markdown",\n   "metadata": {},\n   "source": [')

def proc_img_line(lines, line):
    line = re.sub(r"\s*,\s*$", "", line)
    line = re.sub(r"'(\S+)'", r"'/nbextensions/\1'", line)
    line = re.sub(r"\\\"(\S+)\\\"", r"\"/nbextensions/\1\"", line)

    insert_code_cell_between_markdowns(lines, line, prefix='\n    "%%html\\n",')

def proc_img_line2(lines, line):
    """
    A helper function like below is assumed to be defined in advance:

    def display_image(url):
        from IPython.display import Image, display
        url = os.path.join(root_dir, url)
        display(Image(url))
    """

    m = re.search(r"'(\S+)'", line)
    if m:
        url = m.group(1)
        line = f'    "display_image(\\\"{url}\\\")"'

    insert_code_cell_between_markdowns(lines, line)

def main():
    path = sys.argv[1]
    dirname = os.path.dirname(path)
    basename, ext = os.path.splitext(os.path.basename(path))
    out_path = os.path.join(dirname, "{}_colab{}".format(basename, ext))

    lines = []
    with open(path) as fin:
        for line in fin.readlines():
            line = line.rstrip()
            if re.search(r"img.*src", line):
                proc_img_line2(lines, line)
            else:
                lines.append(line)
    with open(out_path, "w") as fout:
        for line in lines:
            print(line, file=fout)

if __name__ == "__main__":
    main()