連接兩個數據框

Question

我有兩個數據集，進入兩個數據幀

               NAB.AX                                  CBA.AX
                       Close    Volume                                         Close    
    Date                                                  Date
 2013-10-02 06:52:32   36.51   4962900             2013-10-02 06:52:32.082622  21.95  

如您所見，日期格式略有不同。 如何使用日期索引合並兩個數據框。 所以基本上用

2013-10-02 06:52:32

並忽略

.082622

Answer 1

您可以將第二個DataFrame的索引重新分配為numpy datetime64[s]值：

df2.index = df2.index.values.astype('datetime64[s]')

---

例如，

In [58]: df1 = pd.DataFrame({'Close':36.51}, index=pd.DatetimeIndex(['2013-10-02 06:52:32'])); df1

                     Close
2013-10-02 06:52:32  36.51

In [78]: df2 = pd.DataFrame({'Close':[21.95, 22.95, 23.95]}, index=pd.DatetimeIndex(['2013-10-02 06:52:32.082622', '2013-10-02 06:52:32.09', '2013-10-03 06:52:33.09'])); df2
Out[78]: 
                            Close
2013-10-02 06:52:32.082622  21.95
2013-10-02 06:52:32.090000  22.95
2013-10-03 06:52:33.090000  23.95

In [79]: df2.index = df2.index.values.astype('datetime64[s]'); df2
Out[79]: 
                     Close
2013-10-02 06:52:32  21.95
2013-10-02 06:52:32  22.95
2013-10-03 06:52:33  23.95    

In [80]: df1.join(df2, lsuffix='NAB', rsuffix='_CBA')
Out[80]: 
                     CloseNAB  Close_CBA
2013-10-02 06:52:32     36.51      21.95
2013-10-02 06:52:32     36.51      22.95

或者，如果您希望將所有鍵都保留在兩個索引中，請使用外部聯接：

In [81]: df1.join(df2, lsuffix='NAB', rsuffix='_CBA', how='outer')
Out[81]: 
                     CloseNAB  Close_CBA
2013-10-02 06:52:32     36.51      21.95
2013-10-02 06:52:32     36.51      22.95
2013-10-03 06:52:33       NaN      23.95