MATLAB: How do to get a specific time from datetime format in Matlab

datetimeMATLAB

I have these data:
x=(17-Apr-2020 06:59:00,17-Apr-2020 07:00:00,17-Apr-2020 07:01:00,17-Apr-2020,07:02:0017-Apr-2020,07:03:00)
y=(06:58:30,17-Apr-2020 06:59:30,17-Apr-2020 07:00:30,17-Apr-2020 07:01:30,17-Apr-2020 07:02:30,17-Apr-2020 07:03:30)
Both times (x,y) are in the datetime format).
To get the time for x from 07:00:00 till the end I do this:
interpolation_time = (x(420):minutes(1):x(end));
For y I need it from 07:00:30 till the end. How can I do it? It has a different timestamp.
Thank you!

Best Answer

[xh, xm, xs] = hms(x);
xidx = find(xh >= 7 & xm >= 0, 1);
[yh, ym, ys] = hms(y);
yidx = find(yh >= 7 & ym >= 0 & ys >= 30, 1);
selected_x = x(xidx:end);
selected_y = y(yidx:end);
Note here that this code is perfectly happy if the dates do not match at all, and if the entries are out of order. Your problem definition involved finding the first entry that meets a particular time-based criteria that ignores dates.
Perhaps you should use isbetween() ?
See also dateshift() -- for example
xbase = dateshift(x(1), 'start', 'day');
dx = x - xbase;
dy = y - xbase;
maskx = dx >= hours(7);
masky = dy >= hours(7) + seconds(30);
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