How to traverse file system in Python ? Suppose we have given below file structure in our system and we want to traverse all it's branches completely from top to bottom ?

How does os.walk() work in python ?

OS.walk() generate the file names in a directory tree by walking the tree either top-down or bottom-up. For each directory in the tree rooted at directory top (including top itself), it yields a 3-tuple (dirpath, dirnames, filenames).

• root : Prints out directories only from what you specified.
• dirs : Prints out sub-directories from root.
• files : Prints out all files from root and directories.

# Driver function
import os
if __name__ == "__main__":
    for (root,dirs,files) in os.walk('.', topdown=True):
        print (root)
        print (dirs)
        print (files)
        print ('--------------------------------')

Output:

['gfg-article-deep-crawl-master (1)', '.ipynb_checkpoints']
['t.pdf', 'Untitled.ipynb']
--------------------------------
./gfg-article-deep-crawl-master (1)
['gfg-article-deep-crawl-master']
[]
--------------------------------
./gfg-article-deep-crawl-master (1)/gfg-article-deep-crawl-master
['check_rank']
['rank_scraper.py', 'search-page (copy).html', '.gitignore', 'search-page.html', 'globals.py', 'requirements.txt', 'sel_scraper.py', 'README.md']
--------------------------------
./gfg-article-deep-crawl-master (1)/gfg-article-deep-crawl-master/check_rank
[]
['selenium.py', 'tools.py', '__init__.py', 'run_check.py']
--------------------------------
./.ipynb_checkpoints
[]
['Untitled-checkpoint.ipynb']
--------------------------------

Nested List comprehension With Os.Walk

Program to find the python files in the directory tree that means we need to find the files that ends with .py extension.

# code
import os
if __name__ == "__main__": 
  pythonFiles = [file for dirs in os.walk('.', topdown=True)
                     for file in dirs[2] if file.endswith(".py")]
  print('python files in the directory tree are ')
  for r in pythonFiles:
    print(r)

python files in the directory tree are 
Solution.py