FileNotFoundError：文件b'my-directory'不存在

Question

我有一个目录，其中包含许多包含.csv文件的子目录。我的代码是这样的：

walk_dir = 'E:\grams'
print('walk_dir = ' + walk_dir)
walk_dir = os.path.abspath(walk_dir)
print('walk_dir (absolute) = ' + os.path.abspath(walk_dir))
for root, subdirs, files in os.walk(walk_dir):
print('--\nroot = ' + root)
list_file_path = os.path.join(root, 'my-directory-list.txt')
print('list_file_path = ' + list_file_path)

with open(list_file_path, 'wb') as list_file:
    for subdir in subdirs:
        print('\t- subdirectory ' + subdir)

        for filename in files:
         file_path = os.path.join(root, filename)

        print('\t- file %s (full path: %s)' % (filename, file_path))

        with open(file_path, 'rb') as f:
            f_content = f.read()
            df = pd.concat((pd.read_csv(f) for f in files))

运行时出现错误

FileNotFoundError: File b'my-directory-list.txt' does not exist

但是，如果我忽略了代码的最后一行（df = pd.concat((pd.read_csv(f) for f in files))），脚本就可以正常工作。有什么想法吗？