calculating datetime difference in pandas in seconds code example
Example: datediff in seconds in pandas
t1 = pd.to_datetime('1/1/2015 01:00')
t2 = pd.to_datetime('1/1/2015 03:30')
print pd.Timedelta(t2 - t1).seconds / 3600.0
t1 = pd.to_datetime('1/1/2015 01:00')
t2 = pd.to_datetime('1/1/2015 03:30')
print pd.Timedelta(t2 - t1).seconds / 3600.0