合并熊猫中的两列

Question

我有以下Pandas DataFrame：

     date                     at        weight  status    buy_ts               sell_ts
---  -------------------  ------  ------------  --------  -------------------  -------------------
  0  2010-01-03 00:00:00  1.4286             7  buy       2010-01-04 01:47:00  nan
  1  2010-01-03 00:00:00  1.4288             7  buy       2010-01-04 00:00:00  nan
  2  2010-01-03 00:00:00  1.4289             7  buy       2010-01-04 00:00:00  nan
  3  2010-01-04 00:00:00  1.442             25  buy       2010-01-05 00:00:00  nan
  4  2010-01-05 00:00:00  1.4422            15  sell      nan                  2010-01-06 14:03:00
  5  2010-01-05 00:00:00  1.4423            15  sell      nan                  2010-01-06 14:03:00
  6  2010-01-05 00:00:00  1.4424            15  sell      nan                  2010-01-06 14:03:00
  7  2010-01-06 00:00:00  1.4403            18  sell      nan                  2010-01-07 00:04:00
  8  2010-01-06 00:00:00  1.4404            18  sell      nan                  2010-01-07 00:05:00
  9  2010-01-06 00:00:00  1.4405            18  sell      nan                  2010-01-08 08:54:00
 10  2010-01-07 00:00:00  1.4313            26  buy       2010-01-08 00:07:00  nan
 11  2010-01-07 00:00:00  1.4314            26  buy       2010-01-08 00:07:00  nan
 12  2010-01-07 00:00:00  1.4316            26  sell      nan                  2010-01-08 00:10:00

buy_ts和sell_ts包含一个Python datetime.datetime对象

我想创建一个名为merged_ts的新列，其中包含来自buy_ts或sell_ts的datetime.dateime对象（当一列具有值时，另一列始终为nan，因此不可能同时填充两列）。

Answer 1

使用combine_first ：

df['merged'] = df['buy_ts'].combine_first(df['sell_ts'])