filename clean up

cleanup.py

import os.path
import string


VALID_CHARS = "_%s%s" % (string.ascii_letters, string.digits)


def clean_filename_part(part):
    return ''.join(c for c in part if c in VALID_CHARS)


def clean_filename(fname):
    root, ext = os.path.splitext(fname)

    root = clean_filename_part(root)
    ext = clean_filename_part(ext)

    fmt = '{root}.{ext}'
    if not ext:
        fmt = '{root}'
    if not root:
        root = 'noroot'

    return fmt.format(root=root, ext=ext)