如何根据条件筛选出整个组?

created_date 柱以下是数据:

+--------+----------------+-----------------------+---------------------+
| class  |     title      |      description      |    created_date     |
+--------+----------------+-----------------------+---------------------+
| ClassA | ClassA Title 1 | Class A Description 1 | 2017-06-20 21:59:07 |
| ClassA | ClassA Title 2 | Class A Description 2 | 2015-06-20 21:59:07 |
| ClassA | ClassA Title 3 | Class A Description 3 | 2014-06-20 21:59:07 |
| ClassB | ClassB Title 1 | Class A Description 1 | 2016-06-20 21:59:07 |
| ClassB | ClassB Title 2 | Class A Description 2 | 2015-06-20 21:59:07 |
| ClassB | ClassB Title 3 | Class A Description 3 | 2014-06-20 21:59:07 |
| ClassC | ClassC Title 1 | Class C Description 1 | 2017-06-20 21:59:07 |
| ClassC | ClassC Title 2 | Class C Description 2 | 2016-06-20 21:59:07 |
| ClassC | ClassC Title 3 | Class C Description 3 | 2015-06-20 21:59:07 |
+--------+----------------+-----------------------+---------------------+

ClassB 没有任何 创建日期 过去一年。我想过滤掉整个团队 B类 所以我最终只有6张唱片。

我试过使用 filter

df.groupby(["class"]).filter(lambda group: ...))