Python - Iterate and Rename Files

iterate_rename_files.py

# import required module
import os
from pathlib import Path
import re

# assign directory
directory = Path('/Users') / 'thomasnield' / 'git' / 'oreilly_essential_math_for_data_science_book'

def two_digit_correct(filename: str):
    return re.sub(r"(?<=[0-9])_(?=[0-9][A-z])", "_0", filename)

# iterate over files in
# that directory
for chapter_folder in os.scandir(directory):
    if chapter_folder.is_dir():
        print(chapter_folder.path)
        for file in os.scandir(chapter_folder):
            if file.name.endswith(".py"):
                os.rename(os.path.join(chapter_folder.path, file.name), os.path.join(chapter_folder.path, two_digit_correct(file.name)))
                # os.rename(file, two_digit_correct(file.name))