Pandas - convert strings to time without date

问题:

I've read loads of SO answers but can't find a clear solution.

I have this data in a df called day1 which represents hours:

1    10:53 2    12:17 3    14:46 4    16:36 5    18:39 6    20:31 7    22:28 Name: time, dtype: object> 

I want to convert it into a time format. But when I do this:

day1.time = pd.to_datetime(day1.time, format='H%:M%')

The result includes today's date:

1   2015-09-03 10:53:00 2   2015-09-03 12:17:00 3   2015-09-03 14:46:00 4   2015-09-03 16:36:00 5   2015-09-03 18:39:00 6   2015-09-03 20:31:00 7   2015-09-03 22:28:00 Name: time, dtype: datetime64[ns]> 

It seems the format argument isn't working - how do I get the time as shown here without the date?

---

Update

The following formats the time correctly, but somehow the column is still an object type. Why doesn't it convert to datetime64?

day1['time'] = pd.to_datetime(day1['time'], format='%H:%M').dt.time

1    10:53:00 2    12:17:00 3    14:46:00 4    16:36:00 5    18:39:00 6    20:31:00 7    22:28:00 Name: time, dtype: object> 

回答1:

After performing the conversion you can use the datetime accessor dt to access just the hour or time component:

In [51]:  df['hour'] = pd.to_datetime(df['time'], format='%H:%M').dt.hour df Out[51]:         time  hour index              1      10:53    10 2      12:17    12 3      14:46    14 4      16:36    16 5      18:39    18 6      20:31    20 7      22:28    22 

Also your format string H%:M% is malformed, it's likely to raise a ValueError: ':' is a bad directive in format 'H%:M%'

Regarding your last comment the dtype is datetime.time not datetime:

In [53]: df['time'].iloc[0]  Out[53]: datetime.time(10, 53) 

回答2:

You can use to_timedelta

pd.to_timedelta(df+':00') Out[353]:  1   10:53:00 2   12:17:00 3   14:46:00 4   16:36:00 5   18:39:00 6   20:31:00 7   22:28:00 Name: Time, dtype: timedelta64[ns] 

文章来源: Pandas - convert strings to time without date