Using python iterators to recursively list files in a folder

Question

I am trying to list all the TIFF files in a folder using python. I found an answer to this SO question, and adapted its code as follows:

import os
import glob
from itertools import chain

def list_tifs_rec(path):
    return (chain.from_iterable(glob(os.path.join(x[0], '*.tif')) for x in os.walk(path)))

def concatStr(xs):
    return ','.join(str(x) for x in xs)

But I got a runtime error about 'module' object is not callable, when I tried to execute it as follows:

>>> l = list_tifs_rec("d:/temp/")
>>> concatStr(l)

Runtime error 
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "<string>", line 9, in concatStr
  File "<string>", line 9, in <genexpr>
  File "<string>", line 6, in <genexpr>
TypeError: 'module' object is not callable

I come from a C++ background and don't know Python generators very well. I googled around and didn't find close examples of this error, probably because of its generality.

Can anyone please explain the error and how to fix it?

Thanks.

Answer 1

You need to call glob.iglob (the method), not just glob (the module), like so:

glob.iglob(os.path.join(x[0], '*.tif'))

Answer 2

An alternative would be to write a generator function that yields the file paths you need. Similar to your solution but a bit more readable.

def foo(root, file_ext):
    for dirpath, dirnames, filenames in os.walk(root):
        for f_name in filenames:
            if f_name.endswith(file_ext):
                yield os.path.join(dirpath, f_name)

usage

for name in foo(r'folder', 'tif'):
    print name

files = ','.join(foo('c:\pyProjects', 'tiff'))