How can I subtract the times without considering the date in question?
9 views (last 30 days)
Show older comments
I have a vector of time which are linked to dates but I only want to subtract the times from each other without considering the dates too. For example, I want to do 4:30 - 3:30 is equal to 1 hour and then 3:30 - 2:50 is equal to 40 minutes (0.6666667) and etc. I dont want Matlab to consider the date period basically.
I have this code for the time from 25-Apr to 01-May but it does take into account the date too:
out1m=24-(seconds(diff(datetime([T_Smooth{2,4};T_Smooth{3,4}])))/3600);
Can anyone help please? Thank you.
2 Comments
Scott MacKenzie
on 11 Aug 2021
Just to clarify... What result do you expect if you subtract 3:30 on April 26 from 4:30 on April 27? 1 hour or 25 hours?
Accepted Answer
Cris LaPierre
on 11 Aug 2021
Edited: Cris LaPierre
on 11 Aug 2021
% create vector of datetimes
date = datetime(2019,[4;4;5;5],[24;25;1;2],[4;3;2;4],[30;30;50;30],0)
% Take difference of the times.
dt = diff(timeofday(date))
Use the hours function to turn hh:mm:ss into decimal hours if you want.
hours(dt)
More Answers (1)
Scott MacKenzie
on 11 Aug 2021
Edited: Scott MacKenzie
on 11 Aug 2021
Here's one way to do this:
% test data (one month in 30-min increments)
dt = datetime(2021,4,1):minutes(30):datetime(2021,5,1);
% indices of datetime elements to compute hour difference between
n1 = 154;
n2 = 255;
x = datenum(dt(n2) - dt(n1));
hrs = rem(x,1) * 24
5 Comments
Stephen23
on 12 Aug 2021
Edited: Stephen23
on 12 Aug 2021
"what deprecated date functions are you referring to? I only used datetime and minutes in my solution."
You used DATENUM here:
https://www.merriam-webster.com/dictionary/deprecated: "3: to withdraw official support for or discourage the use of (something, such as a software product) in favor of a newer or better alternative."
The DATENUM documentation currently contains this note:
Scott MacKenzie
on 12 Aug 2021
Oops, yes, I used datenum as well. Thanks for pointing that out. The language to discourage use of this function could be a tad stronger, however. Below is what appears for xlsread, as an example.
See Also
Categories
Find more on Dates and Time in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!