Seeking help regarding Python code

[Debasree Banerjee]

Hi,

I have a dataset like this:



RecTime

NO2_RAW

NO2

LAQN_NO2

10980

06/6/19 01:45

17.95444444

53.46255556

17.7

10981

06/6/19 01:45

17.94444444

53.44344444

17.7

10982

06/6/19 01:45

17.92111111

53.39877778

17.7

I want to calculate the difference between LAQN_NO2 and NO2_RAW everyday at
04:00 and add that value to NO2_RAW values in all rows on a particular day.
I have 2 months of data and I want to do this for each day.
So, I want a table like this



RecTime

NO2_RAW

NO2

LAQN_NO2

NO2_Cal

10980

06/6/19 01:45

17.95444444

53.46255556

17.7

(LAQN_NO2-NO2_RAW)+NO2_RAW

10981

06/6/19 01:45

17.94444444

53.44344444

17.7



10982

06/6/19 01:45

17.92111111

53.39877778

17.7



Can someone please help?

Thanks
Debasree