Rename numbered file names to padded variant

rename_numbered.py

import os
import math

def rename(basename, basename2=None, extension=None, directory="."):
    """Rename all XXX1.ext, XXX123.ext files to XXX001.ext, ..."""
    if basename2 is None:
        basename2 = basename
    files = [name for name in os.listdir(directory) if name.startswith(basename)] 
    if extension:
        files = [name for name in files if name.endswith(extension)]
    digits = int(math.ceil(math.log10(len(files))))
    for name in files:
        base, ext = os.path.splitext(name)
        number = base[len(basename):]
        number = number.zfill(digits)
        new_name = basename2 + number + ext
        os.rename(name, new_name)