Add date stamp to time stamp

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vicsm on 1 Nov 2019
Commented: vicsm on 1 Nov 2019
I have a 270176x15 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!

Accepted Answer

Guillaume on 1 Nov 2019
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 Whatever you do don't use outdated datenum and datestr.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
This assumes of course that days aren't skipped. But since you've lost that information, there's no way to know.
  1 Comment
vicsm on 1 Nov 2019
THANK YOU so much! This solved my problem completely!

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More Answers (1)

Sulaymon Eshkabilov
Sulaymon Eshkabilov on 1 Nov 2019
these commands will resolve your task:
load BB
DATES = datestr(EEE, 'mm/dd/yy');
You'd need to adjust the starting day or end day.
Good luck.
vicsm on 1 Nov 2019
Edited: vicsm on 1 Nov 2019
But the date doesn't change from 23:59:59 to 00:00:00; it's still 10/30/19 and instead it should be 11/01/19. Maybe I'm not explaining myself properly...
I need it to look like this:
23:59:56 10/30/19
23:59:57 10/30/19
23:59:58 10/30/19
23:59:59 10/30/19
00:00:00 11/01/19
00:00:01 11/01/19
00:00:02 11/01/19

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