[英]How to filter out an entire group based on condition?
我想刪除created_date
列中過去一年沒有任何值的組。 數據如下:
+--------+----------------+-----------------------+---------------------+
| 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 |
+--------+----------------+-----------------------+---------------------+
如果您在上述數據中看到,則只有ClassB
組在過去的一年中沒有任何created_date
。 我想過濾掉整個組ClassB
所以最終只有6條記錄。
我嘗試使用filter
,但不確定如何處理lamda內的分組:
df.groupby(["class"]).filter(lambda group: ...))
假設您的截止日期是date
f = lambda df: not df[df.created_date >= date].empty
df.groupby('class').filter(f)
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