[python] Get a filtered list of files in a directory

I am trying to get a list of files in a directory using Python, but I do not want a list of ALL the files.

What I essentially want is the ability to do something like the following but using Python and not executing ls.

ls 145592*.jpg

If there is no built-in method for this, I am currently thinking of writing a for loop to iterate through the results of an os.listdir() and to append all the matching files to a new list.

However, there are a lot of files in that directory and therefore I am hoping there is a more efficient method (or a built-in method).

Preliminary code

import glob
import fnmatch
import pathlib
import os

pattern = '*.py'
path = '.'

Solution 1 - use "glob"

# lookup in current dir
glob.glob(pattern)

In [2]: glob.glob(pattern)
Out[2]: ['wsgi.py', 'manage.py', 'tasks.py']

Solution 2 - use "os" + "fnmatch"

Variant 2.1 - Lookup in current dir

# lookup in current dir
fnmatch.filter(os.listdir(path), pattern)

In [3]: fnmatch.filter(os.listdir(path), pattern)
Out[3]: ['wsgi.py', 'manage.py', 'tasks.py']

Variant 2.2 - Lookup recursive

# lookup recursive
for dirpath, dirnames, filenames in os.walk(path):

    if not filenames:
        continue

    pythonic_files = fnmatch.filter(filenames, pattern)
    if pythonic_files:
        for file in pythonic_files:
            print('{}/{}'.format(dirpath, file))

Result

./wsgi.py
./manage.py
./tasks.py
./temp/temp.py
./apps/diaries/urls.py
./apps/diaries/signals.py
./apps/diaries/actions.py
./apps/diaries/querysets.py
./apps/library/tests/test_forms.py
./apps/library/migrations/0001_initial.py
./apps/polls/views.py
./apps/polls/formsets.py
./apps/polls/reports.py
./apps/polls/admin.py

Solution 3 - use "pathlib"

# lookup in current dir
path_ = pathlib.Path('.')
tuple(path_.glob(pattern))

# lookup recursive
tuple(path_.rglob(pattern))

Notes:

1. Tested on the Python 3.4
2. The module "pathlib" was added only in the Python 3.4
3. The Python 3.5 added a feature for recursive lookup with glob.glob https://docs.python.org/3.5/library/glob.html#glob.glob. Since my machine is installed with Python 3.4, I have not tested that.

you might also like a more high-level approach (I have implemented and packaged as findtools):

from findtools.find_files import (find_files, Match)


# Recursively find all *.txt files in **/home/**
txt_files_pattern = Match(filetype='f', name='*.txt')
found_files = find_files(path='/home', match=txt_files_pattern)

for found_file in found_files:
    print found_file

can be installed with

pip install findtools

Filenames with "jpg" and "png" extensions in "path/to/images":

import os
accepted_extensions = ["jpg", "png"]
filenames = [fn for fn in os.listdir("path/to/images") if fn.split(".")[-1] in accepted_extensions]

Another option:

>>> import os, fnmatch
>>> fnmatch.filter(os.listdir('.'), '*.py')
['manage.py']

https://docs.python.org/3/library/fnmatch.html

Filter with glob module:

Import glob

import glob

Wild Cards:

files=glob.glob("data/*")
print(files)

Out:

['data/ks_10000_0', 'data/ks_1000_0', 'data/ks_100_0', 'data/ks_100_1',
'data/ks_100_2', 'data/ks_106_0', 'data/ks_19_0', 'data/ks_200_0', 'data/ks_200_1', 
'data/ks_300_0', 'data/ks_30_0', 'data/ks_400_0', 'data/ks_40_0', 'data/ks_45_0', 
'data/ks_4_0', 'data/ks_500_0', 'data/ks_50_0', 'data/ks_50_1', 'data/ks_60_0', 
'data/ks_82_0', 'data/ks_lecture_dp_1', 'data/ks_lecture_dp_2']

Fiter extension .txt:

files = glob.glob("/home/ach/*/*.txt")

A single character

glob.glob("/home/ach/file?.txt")

Number Ranges

glob.glob("/home/ach/*[0-9]*")

Alphabet Ranges

glob.glob("/home/ach/[a-c]*")

import os

dir="/path/to/dir"
[x[0]+"/"+f for x in os.walk(dir) for f in x[2] if f.endswith(".jpg")]

This will give you a list of jpg files with their full path. You can replace x[0]+"/"+f with f for just filenames. You can also replace f.endswith(".jpg") with whatever string condition you wish.

You can use pathlib that is available in Python standard library 3.4 and above.

from pathlib import Path

files = [f for f in Path.cwd().iterdir() if f.match("145592*.jpg")]

glob.glob() is definitely the way to do it (as per Ignacio). However, if you do need more complicated matching, you can do it with a list comprehension and re.match(), something like so:

files = [f for f in os.listdir('.') if re.match(r'[0-9]+.*\.jpg', f)]

More flexible, but as you note, less efficient.

You can use subprocess.check_ouput() as

import subprocess

list_files = subprocess.check_output("ls 145992*.jpg", shell=True) 

Of course, the string between quotes can be anything you want to execute in the shell, and store the output.

Keep it simple:

import os
relevant_path = "[path to folder]"
included_extensions = ['jpg','jpeg', 'bmp', 'png', 'gif']
file_names = [fn for fn in os.listdir(relevant_path)
              if any(fn.endswith(ext) for ext in included_extensions)]

I prefer this form of list comprehensions because it reads well in English.

I read the fourth line as: For each fn in os.listdir for my path, give me only the ones that match any one of my included extensions.

It may be hard for novice python programmers to really get used to using list comprehensions for filtering, and it can have some memory overhead for very large data sets, but for listing a directory and other simple string filtering tasks, list comprehensions lead to more clean documentable code.

The only thing about this design is that it doesn't protect you against making the mistake of passing a string instead of a list. For example if you accidentally convert a string to a list and end up checking against all the characters of a string, you could end up getting a slew of false positives.

But it's better to have a problem that's easy to fix than a solution that's hard to understand.

How about str.split()? Nothing to import.

import os

image_names = [f for f in os.listdir(path) if len(f.split('.jpg')) == 2]

use os.walk to recursively list your files

import os
root = "/home"
pattern = "145992"
alist_filter = ['jpg','bmp','png','gif'] 
path=os.path.join(root,"mydir_to_scan")
for r,d,f in os.walk(path):
    for file in f:
        if file[-3:] in alist_filter and pattern in file:
            print os.path.join(root,file)

You can define pattern and check for it. Here I have taken both start and end pattern and looking for them in the filename. FILES contains the list of all the files in a directory.

import os
PATTERN_START = "145592"
PATTERN_END = ".jpg"
CURRENT_DIR = os.path.dirname(os.path.realpath(__file__))
for r,d,FILES in os.walk(CURRENT_DIR):
    for FILE in FILES:
        if PATTERN_START in FILE.startwith(PATTERN_START) and PATTERN_END in FILE.endswith(PATTERN_END):
            print FILE