Code Review Stack Exchange is a question and answer site for peer programmer code reviews. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

Given a base path and a list with extensions the task is to list all files:

Two of my solutions are:

from glob import glob
from os import path

EXTENSIONS = ['*.zip', '*.jar', '*.pdf']
DOC_PATH = '/path/to/files'

# Solution1:
files = []         
for ext in EXTENSIONS:
    files.extend(glob(path.join(DOC_PATH, ext)))
# works but looks very clumsy

# Solution2:
files = reduce(lambda x,y: x+y,
               [glob(path.join(DOC_PATH, ext)) for ext in EXTENSIONS])
# Also functional but looks like a misuse of reduce

Have you got any other ideas?

share|improve this question
Not quite sure how idiomatic/efficient it is : sum((glob(path.join(DOC_PATH, ext)) for ext in EXTENSIONS), []) . – Josay Jul 7 '14 at 12:20
up vote 3 down vote accepted

If you only need to iterate over them (once) and not an actual list, you could use itertools.chain and glob.iglob:

files = chain(*(iglob(path.join(DOC_PATH, ext)) for ext in EXTENSIONS))

If you do need an actual list, you can further call list(files), of course.

share|improve this answer
chain is quite a good idea – ProfHase85 Jul 7 '14 at 12:35

Using os.listdir and os.path.splitext:

import os
EXTENSIONS = 'zip jar pdf'.split()
EXTENSION_SET = set('.' + e for e in EXTENSIONS)
files = [f for f in os.listdir(DOC_PATH) if os.path.splitext(f)[1] in EXTENSION_SET]

Using os.listdir and

import os
import re
EXTENSIONS = 'zip jar pdf'.split()
EXTENSION_RE = re.compile(r'\.({})$'.format('|'.join(EXTENSIONS))
files = [f for f in os.listdir(DOC_PATH) if]
# or files = list(filter(, os.listdir(DOC_PATH)))

The advantage of these approaches is that you only iterate over the files in the directory once (rather than once for each extension, as in the glob case).

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.