generate file list using regex

regex_file_list.py

import re
file_list =[]
# get regex range from web generator - https://3widgets.com/
# find range of files from filename_1981.nc to filename_2018.nc
regexp = re.compile('filename_(198[1-9]|199[0-9]|200[0-9]|201[0-8]).nc')
ROOT_DIR ='/root/path/to/files/'
for root, dirs, files in os.walk(ROOT_DIR):
    for file in files:
        if regexp.search(file):
            file_list.append(os.path.join(root, file))

file_list.sort()
file_list