Recursive sub folder search and return files in a

Question

I am working on a script to recursively go through subfolders in a mainfolder and build a list off a certain file type. I am having an issue with the script. Its currently set as follows

for root, subFolder, files in os.walk(PATH):
    for item in files:
        if item.endswith(".txt") :
            fileNamePath = str(os.path.join(root,subFolder,item))

the problem is that the subFolder variable is pulling in a list of subfolders rather than the folder that the ITEM file is located. I was thinking of running a for loop for the subfolder before and join the first part of the path but I figured Id double check to see if anyone has any suggestions before that. Thanks for your help!

Answer 1

I will translate John La Rooy's list comprehension to nested for's, just in case anyone else has trouble understanding it.

result = [y for x in os.walk(PATH) for y in glob(os.path.join(x[0], '*.txt'))]

Should be equivalent to:

result = []

for x in os.walk(PATH):
    for y in glob(os.path.join(x[0], '*.txt')):
        result_for.append(y)

Here's the documentation for list comprehension and the functions os.walk and glob.glob.

Answer 2

Changed in Python 3.5: Support for recursive globs using “**”.

glob.glob() got a new recursive parameter.

If you want to get every .txt file under my_path (recursively including subdirs):

import glob

files = glob.glob(my_path + '/**/*.txt', recursive=True)

# my_path/     the dir
# **/       every file and dir under my_path
# *.txt     every file that ends with '.txt'

If you need an iterator you can use iglob as an alternative:

for file in glob.iglob(my_path, recursive=False):
    # ...

Answer 3

You should be using the dirpath which you call root. The dirnames are supplied so you can prune it if there are folders that you don't wish os.walk to recurse into.

import os
result = [os.path.join(dp, f) for dp, dn, filenames in os.walk(PATH) for f in filenames if os.path.splitext(f)[1] == '.txt']

Edit:

After the latest downvote, it occurred to me that glob is a better tool for selecting by extension.

import os
from glob import glob
result = [y for x in os.walk(PATH) for y in glob(os.path.join(x[0], '*.txt'))]

Also a generator version

from itertools import chain
result = (chain.from_iterable(glob(os.path.join(x[0], '*.txt')) for x in os.walk('.')))

Edit2 for Python 3.4+

from pathlib import Path
result = list(Path(".").rglob("*.[tT][xX][tT]"))

Answer 4

The new pathlib library simplifies this to one line:

from pathlib import Path
result = list(Path(PATH).glob('**/*.txt'))

You can also use the generator version:

from pathlib import Path
for file in Path(PATH).glob('**/*.txt'):
    pass

This returns Path objects, which you can use for pretty much anything, or get the file name as a string by file.name.

Answer 5

Its not the most pythonic answer, but I'll put it here for fun because it's a neat lesson in recursion

def find_files( files, dirs=[], extensions=[]):
    new_dirs = []
    for d in dirs:
        try:
            new_dirs += [ os.path.join(d, f) for f in os.listdir(d) ]
        except OSError:
            if os.path.splitext(d)[1] in extensions:
                files.append(d)

    if new_dirs:
        find_files(files, new_dirs, extensions )
    else:
        return

On my machine I have two folders, root and root2

mender@multivax ]ls -R root root2
root:
temp1 temp2

root/temp1:
temp1.1 temp1.2

root/temp1/temp1.1:
f1.mid

root/temp1/temp1.2:
f.mi  f.mid

root/temp2:
tmp.mid

root2:
dummie.txt temp3

root2/temp3:
song.mid

Lets say I want to find all .txt and all .mid files in either of these directories, then I can just do

files = []
find_files( files, dirs=['root','root2'], extensions=['.mid','.txt'] )
print(files)

#['root2/dummie.txt',
# 'root/temp2/tmp.mid',
# 'root2/temp3/song.mid',
# 'root/temp1/temp1.1/f1.mid',
# 'root/temp1/temp1.2/f.mid']