How to calculate time difference between two pandas column [duplicate]

Answer 1

You need omit pd.Timedelta, because difference of times return timedeltas:

df_time['td'] = df_time['stop']-df_time['start']
print (df_time)
                start                stop               td
0 2015-11-04 10:12:00 2015-11-06 06:38:00  1 days 20:26:00
1 2015-11-04 10:23:00 2015-11-05 08:30:00  0 days 22:07:00
2 2015-11-04 14:01:00 2015-11-17 10:34:00 12 days 20:33:00

EDIT: Another solution is subtract numpy arrays:

df_time['td'] = df_time['stop'].values - df_time['start'].values
print (df_time)
                start                stop               td
0 2015-11-04 10:12:00 2015-11-06 06:38:00  1 days 20:26:00
1 2015-11-04 10:23:00 2015-11-05 08:30:00  0 days 22:07:00
2 2015-11-04 14:01:00 2015-11-17 10:34:00 12 days 20:33:00

Answer 2

First make sure that you have dates in your column

data.loc[:, 'start'] = pd.to_datetime(data.loc[:, 'start'])
data.loc[:, 'stop'] = pd.to_datetime(data.loc[:, 'stop'])

Then substract

data['delta'] = data['stop'] - data['start']