Q:

When I subtract two timestamps in a dataframe ,I am getting output "0 days 00:07:30" ; How do I convert it into minutes? 

diff=table['DelayInMinute']=(pd.to_datetime(table['joinTime']) - 
     pd.to_datetime(table['ScheduleDateTime']))

Output: "0 days 00:00:00"

diff_minute=pd. Timedelta(diff).total_seconds()/60.0;

But getting 

ValueError: Value must be Timedelta, string, integer, float, timedelta
  or convertible

A:

You can use Series.dt.total_seconds if multiple values of Series:
diff_minute=diff.dt.total_seconds()/60.0

If want output scalar by first value use iat for select first value with Timedelta.total_seconds, converting to Timedelta is not necessary:
diff_minute=diff.iat[0].total_seconds()/60.0

