How to loop through files of certain extensions?

Question

I'm trying to loop through a folder and all subfolders to find all files of certain file types - for example, only .mp4, .avi, .wmv.

Here is what I have now, it loops through all file types:

import os
rootdir = 'input'

for subdir, dirs, files in os.walk(rootdir):
     for file in files:
          print (os.path.join(subdir, file))

Answer 1

For multiple extensions, the simplest is just to use str.endswith passing a tuple of substrings to check:

  for file in files:
      if file.endswith((".avi",".mp4","wmv")):
         print (os.path.join(subdir, file))

You could use iglob like below and chain the searches returned or use re.search but using endswith is probably the best approach.

from itertools import chain
from glob import iglob

for subdir, dirs, files in os.walk(rootdir):
    for file in chain.from_iterable(iglob(os.path.join(rootdir,p)) for p in ("*.avi", "*.mp4", "*wmv")) :
            print(os.path.join(subdir, file))

Using python3.5 glob now supports recursive searches with the ** syntax:

from itertools import chain
from glob import iglob

from glob import iglob
for file in chain.from_iterable(iglob(os.path.join(rootdir,p)) 
      for p in (rootdir+"**/*.avi", "**/*.mp4", "**/*wmv")):
          print(file)

Answer 2

You can use os.path.splitext which takes a path and splits the file extension from the end of it:

import os
rootdir = 'input'
extensions = ('.mp4', '.avi', '.wmv')

for subdir, dirs, files in os.walk(rootdir):
    for file in files:
        ext = os.path.splitext(file)[-1].lower()
        if ext in extensions:
            print (os.path.join(subdir, file))