I have a df of minutely prices and want to establish if there are minutes missing (across a 5 year period). The price is only stamped when there is a transaction so there are some missing minutes.
There are 4 entities in a different column and I would like to know the entity that is missing the minute as well as when it was.
My first inclination is to resample and sum NaNs. What is the best way of doing this?