Difference between two timestamps in Pandas

问题

I have the following two time column,"Time1" and "Time2".I have to calculate the "Difference" column,which is (Time2-Time1) in Pandas:

Time1         Time2                 Difference
8:59:45       9:27:30               -1 days +23:27:45
9:52:29       10:08:54              -1 days +23:16:26
8:07:15       8:07:53               00:00:38

When Time1 and Time2 are in different hours,I am getting result as"-1 days +" .My desired output for First two values are given below:

Time1         Time2                 Difference
8:59:45       9:27:30               00:27:45
9:52:29       10:08:54              00:16:26

How can I get this output in Pandas?

Both time values are in 'datetime64[ns]' dtype.

回答1:

The issue is not that time1 and time2 are in different hours, it's that time2 is before time1 so time2-time1 is negative, and this is how negative timedeltas are stored. If you just want the difference in minutes as a negative number, you could extract the minutes before calculating the difference:

(df.Time1.dt.minute- df.Time2.dt.minute)

回答2:

I was not able to reproduce the issue using pandas 17.1:

import pandas as pd

d = {
    "start_time": [
        "8:59:45",
        "9:52:29",
        "8:07:15"
    ],
    "end_time": [
        "9:27:30",
        "10:08:54",
        "8:07:53"
    ]
}

from datetime import  datetime
df = pd.DataFrame(data=d)
df['start_time'] = pd.to_datetime(df['start_time'])
df['end_time'] = pd.to_datetime(df['end_time'])

df.end_time - df.start_time

0   00:27:45
1   00:16:25
2   00:00:38
dtype: timedelta64[ns]

来源：https://stackoverflow.com/questions/33433452/difference-between-two-timestamps-in-pandas