Batch Renaming of Files in a Directory

Question

Is there an easy way to rename a group of files already contained in a directory, using Python?

Example: I have a directory full of *.doc files an

Answer 1

I have this to simply rename all files in subfolders of folder

import os

def replace(fpath, old_str, new_str):
    for path, subdirs, files in os.walk(fpath):
        for name in files:
            if(old_str.lower() in name.lower()):
                os.rename(os.path.join(path,name), os.path.join(path,
                                            name.lower().replace(old_str,new_str)))

I am replacing all occurences of old_str with any case by new_str.