my_list = [91, 42, 27, 39, 24, 45, 53]

print("列表是：")
print(my_list)

my_ordered_dict = dict(zip(list(set(my_list)), range(len(set(my_list)))))

my_result = [my_ordered_dict[elem] for elem in my_list]

print("结果是：")
print(my_result)

列表是：
[91, 42, 27, 39, 24, 45, 53]
结果是：
[0, 2, 6, 1, 5, 3, 4]