pandas:对于df复制行中的每一行N次略有变化

Question

所以我有一个像这样的DataFrame:

   N    start
1  1    08/01/2014 9:30:02
2  1    08/01/2014 10:30:02 
3  2    08/01/2014 12:30:02
4  3    08/01/2014 4:30:02

我需要复制每一行N次,每次增加一小时,如下所示:

   N    start
1  1    08/01/2014 9:30:02
2  1    08/01/2014 10:30:02 
3  2    08/01/2014 12:30:02
3  2    08/01/2014 13:30:02
4  3    08/01/2014 4:30:02
4  3    08/01/2014 5:30:02
4  3    08/01/2014 6:30:02

我怎么能在熊猫里做到这一点？

Answer 1

您可以使用reindex扩展DataFrame,使用TimedeltaIndex来添加小时:

import pandas as pd
df = pd.DataFrame({'N': [1, 1, 2, 3],
                   'start': ['08/01/2014 9:30:02',
                             '08/01/2014 10:30:02',
                             '08/01/2014 12:30:02',
                             '08/01/2014 4:30:02']})
df['start'] = pd.to_datetime(df['start'])
df = df.reindex(np.repeat(df.index.values, df['N']), method='ffill')
df['start'] += pd.TimedeltaIndex(df.groupby(level=0).cumcount(), unit='h')

产量

   N               start
0  1 2014-08-01 09:30:02
1  1 2014-08-01 10:30:02
2  2 2014-08-01 12:30:02
2  2 2014-08-01 13:30:02
3  3 2014-08-01 04:30:02
3  3 2014-08-01 05:30:02
3  3 2014-08-01 06:30:02