Iterate over all filenames in a directory tree

filepaths.py

import os

def filepaths(rootdir, ext_filter=None):
    if isinstance(ext_filter, basestring):
        _filter = lambda p: p.endswith(ext_filter)
    elif isinstance(ext_filter, tuple):
        _filter = lambda p: os.path.splitext(p)[1] in ext_filter
    else:
        _filter = ext_filter

    for root, subfolders, files in os.walk(rootdir):
        for filename in files:
            path = os.path.abspath(os.path.join(root, filename))
            if not _filter or _filter(path):
                yield path