Python Pandas: Combine Two Dataframes By Date Index And A Common Column Value

There are two dateframes, one is df1, another is df2 as follows: df1: a b id 2010-01-01 1 4 21 2010-01-01 2 5 22 2010-01-01 3 6 23 20

Solution 1:

IIUC:

In [388]: df2.set_index('id', append=True).join(df1.set_index('id', append=True)) \
             .reset_index(level='id')
Out[388]:
            id  c  d  a  b
2010-01-02  21  1  4  1  4
2010-01-02  22  2  5  2  5
2010-01-02  23  3  6  3  6
2010-01-02  24  4  7  4  7
2010-01-03  21  1  4  1  4
2010-01-03  22  2  5  2  5
2010-01-03  23  3  6  3  6
2010-01-03  24  4  7  4  7