MATLAB: Add date stamp to time stamp

datedatetimetime

Hi,
I have a 270176×15 table (see attached a reduced version of it, called BB.mat) where one of my arrays is Time (with measurements every second). Date stamp is missing, and I have two questions about this:
1) How can I add the date stamp (Date) that changes accordingly to my Time (i.e. changes day from 23:59 to 00:00) IF
2) (IF) the only date reference I have is: my last timestamp (i.e. 16:05:07) corresponds to 21/05/2018? (so basically I know the end date but not the start date).
Does anyone know how to do this? Any help will be very much appreciated!

Best Answer

Here's how I'd do it. Whatever you do don't use outdated datenum and datestr. Stay with datetime and duration arrays.
[h, m, s] = hms(HRV_BB3.Time(end));  %extract hours, minutes and seconds from last time (actually a datetime whose date is wrong)
enddate = datetime(2018,5,21,h,m,s)  %calculate the right datetime
HRV_BB3.DateTime = enddate + [cumsum(-mod(diff(HRV_BB3.Time), hours(24)), 'reverse'); 0];  %calculate difference between consecutive dates, modulo 24h, and add that back
Done!
This assumes of course that days aren't skipped. But since you've lost that information, there's no way to know.
Related Question