python implements a method to filter out all files under a folder that do not end with py files

As shown below:

dir_in = os.path.join(os.path.dirname(__file__), r"oldApp")
    dir_in = unicode(dir_in, r"GBK")
    dir_out = os.path.join(os.path.dirname(__file__), r"newApp")
    dir_out = unicode(dir_out, r"GBK")


    rediret_file_path_list = []
    soure_file_path_out_list = []
    for root, dirs, files in os.walk(dir_in):
        for file in files:
            # print('root=%s' %root)
            # print('1111 file=%s' %file)
            # filter file extend name not .py
            filter_file = file.split('.')
            if filter_file[1] != 'py':
                continue


            soure_file_path_out = os.path.join(root, file)
            # print(soure_file_path_out)
            soure_file_path_out_list.append(soure_file_path_out)
            root_new = root.replace(r'oldApp', r'newApp')
            if not os.path.exists(root_new):
                os.makedirs(root_new)
            rediret_file_path = os.path.join(root_new, file)
            # print('rediret_file_path=%s' %rediret_file_path)
            rediret_file_path_list.append(rediret_file_path)