在 pandas df/series上使用.groupby()后如何预览行

问题描述

使用df.groupby(df.index.month)后，我想预览我的DataFrame，但是.head删除了组格式，并且df['col'][:3]返回以下错误:

After using df.groupby(df.index.month) I would like to preview my DataFrame unfortunately .head removes the group formatting and df['col'][:3] returns the following error:

---------------------------------------------------------------------------
NotImplementedError                       Traceback (most recent call last)
<ipython-input-154-6783abceafb8> in <module>()
      1 test= sve_DOC
      2 test = test.groupby(test.index.month)
----> 3 print test['DOC_mg/L'][:3]

C:\Users\AppData\Local\Enthought\Canopy32\User\lib\site-packages\pandas\core\groupby.pyc in __getitem__(self, key)
    487 
    488     def __getitem__(self, key):
--> 489         raise NotImplementedError
    490 
    491     def _make_wrapper(self, name):

NotImplementedError: 

有什么办法解决这个问题吗?

Is there any way around this?

更新:检查完组后，我想根据@chrisb的帖子test.get_group(5)['col'].median()

Update: After checking the groups I wanted to do some which operations on the data which I did based on @chrisb's post test.get_group(5)['col'].median()

推荐答案

是这样的吗? gb是GroupBy对象.这将打印出前3组中的前5行.

Something like this? gb is the GroupBy object. This prints the first 5 rows from the first 3 groups.

In [230]: gb = df.groupby(df.index.month)

In [231]: for k in gb.groups.keys()[:3]:
     ...:     print gb.get_group(k)[:5]

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