在pandas数据帧中一起添加两个时间列？

Question

I have the following data:

 time_begin  DRTN_IN_SCND
 16:22:16           439
 16:29:37            53
 16:30:33            85

I would like to make a new column that adds time_begin and DRTN_IN_SCND (the duration in seconds) to create a new time.

I have tried:

df['new_time'] = df['time_begin'].apply(lambda x: (dt.datetime.combine(dt.datetime(1,1,1), x,) + dt.timedelta(seconds=df.DRTN_IN_SCND)).time())

This works if dt.timedelta(seconds=3) but does not work when I change to dt.timedelta(seconds=df.DRTN_IN_SCND). I get the following error.

TypeError: unsupported type for timedelta seconds component: Series

Does anyone know how to fix this or of another way to accomplish what I'm trying to do? Thanks!

Answer 1

You'll have to convert the DRTN_IN_SCND and time_begin to time deltas if you want to do properly calculations on the columns, pandas has to_timedelta which is pretty handy:

df['DRTN_IN_SCND'] = pd.to_timedelta(df['DRTN_IN_SCND'], unit='s')
df['time_begin'] = pd.to_timedelta(df['time_begin'])
df['new_time'] = df['time_begin'] + df['DRTN_IN_SCND']

This will give you the new column new_time :

   time_begin  DRTN_IN_SCND  new_time
0    16:22:16      00:07:19  16:29:35
1    16:29:37      00:00:53  16:30:30
2    16:30:33      00:01:25  16:31:58

Answer 2

Problem

You are using apply on df['new_time'] which is a series and in the lambda you are referring to df.DRTN_IN_SCND which is another series. So the error states that you are trying to add a time object to a series object and it doesn't know what to do.

Solution

Instead, use apply on the dataframe. In this context, the x 's in the lambda function are series and you can access each component via ix . This does what you want.

df['new_time'] = df.apply(lambda x: x.ix['time_begin'] + dt.timedelta(seconds=x.ix['DRTN_IN_SCND']), axis=1)