当DateTime索引不是唯一且对应的值相同时重新采样 [英] Resampling when the DateTime index is not unique and the corresponding value is the same

问题描述

我有以下df DataFrame(pandas):

I have the following df DataFrame (pandas):

           attribute
2017-01-01         a
2017-01-01         a
2017-01-05         b
2017-02-01         a
2017-02-10         a

其中第一列是一个非唯一的datetime索引，我想每周计算a和b的数量.如果我尝试df.attribute.resample('W').count()，将由于输入重复而出现错误.

where the first column is a non-unique datetime index and I want to count the number of a's and b's on a weekly basis. If I try to df.attribute.resample('W').count() there will be an error, because of duplicate entries.

我该怎么做?

推荐答案

您可能会对包含groupby和resample的两步过程感兴趣.

You might be interested in a 2-step process involving a groupby followed by a resample.

df.groupby(level=0).count().resample('W').sum()
            attribute
2017-01-01        2.0
2017-01-08        1.0
2017-01-15        NaN
2017-01-22        NaN
2017-01-29        NaN
2017-02-05        1.0
2017-02-12        1.0

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