pandas 从数据框熊猫创建多索引
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create multiindex from dataframe pandas
提问by EdChum
I'm trying to create the multi-index dataframe from following dataframe:
我正在尝试从以下数据帧创建多索引数据帧：
date_time session
2015-07-30 10:32:54.000 1
2015-07-30 10:32:54.000 1
2015-07-30 10:36:39.000 1
2015-07-30 10:36:39.000 1
........................ 1
2015-07-30 11:58:57.000 2
2015-07-30 12:18:37.000 2
2015-07-30 12:28:51.000 2
to obtain smth like:
获得 smth 像：
date_time session
2015-07-30 10:32:54.000 1
2015-07-30 10:32:54.000
2015-07-30 10:36:39.000
2015-07-30 10:36:39.000
........................
2015-07-30 11:58:57.000 2
2015-07-30 12:18:37.000
2015-07-30 12:28:51.000
....................... 3
guiding by the answers for this question: MultiIndex Group By in Pandas Data Frame
以这个问题的答案为指导： Pandas Data Frame 中的 MultiIndex Group By
I tried this code for my data:
我为我的数据尝试了这个代码：
def create_multi():
multi=df.set_index(['session', 'date'], inplace=True)
print multi
but it returns NoneI don't know if this method is appropriate for what I need to do and I just use it not correctly, or I should use another method
但它返回 None我不知道这个方法是否适合我需要做的事情，我只是没有正确使用它，或者我应该使用另一种方法
回答by EdChum
You passed inplace=Trueso it's performed inplace surprisingly enough so returns nothing when you assigned to multi.
您通过了，inplace=True因此它在原地执行得足够令人惊讶，因此当您分配给multi.
def create_multi():
multi=df.set_index(['session', 'date'], inplace=False)
print multi
The above would work, check the docs, note that the default is inplace=Falseso it's strictly not necessary to specify if you want that behaviour
上面的方法可行，检查文档，注意默认是inplace=False这样的，所以没有必要指定你是否想要这种行为
