Get specific number of timetable rows after specific timedate

Question

Daniele Lupo 2020-4-5

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https://ww2.mathworks.cn/matlabcentral/answers/515569-get-specific-number-of-timetable-rows-after-specific-timedate

评论： Ameer Hamza 2020-4-5

I've a timetable like the following one:

intersectionPoints =
  10×1 timetable
         Timestamp          Value 
    ____________________    ______
    01-Feb-2016 00:00:00    1.0848
    01-Feb-2016 01:00:00    1.0847
    01-Feb-2016 04:00:00    1.0848
    02-Feb-2016 14:07:44    1.0914
    02-Feb-2016 17:21:36    1.0916
    03-Feb-2016 01:49:18    1.0917
    03-Feb-2016 07:18:43    1.0919
    04-Feb-2016 00:53:20    1.1088
    04-Feb-2016 04:18:16    1.1097
    04-Feb-2016 21:38:10    1.1199
    

I also have a datetime object representing a date between the first and last value of my timetable:

    checkDate = 
  datetime
   03-Feb-2016 01:49:20

Now I want to retrieve two rows of my table. The row with the timestap that's just before my checkDate and the row just after it. In my case I need to retrieve these two rows:

   % just before 03-Feb-2016 01:49:20
   03-Feb-2016 01:49:18    1.0917
   % just after 03-Feb-2016 01:49:20
   03-Feb-2016 07:18:43    1.0919

I've seen that I can use timerange for it, but's not suited for my purposes. I need to set a start datetime and an end timedate for defining a timerange, and I don't know the distance between samples in my timetable, so I can miss values. I can have timetables where time intervals between consecutive rows span between one second and many years (they're result of some preprocessing).

Is there a way to obtain my result without using timerange or some linear search?

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Answer 1

Ameer Hamza 2020-4-5

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/515569-get-specific-number-of-timetable-rows-after-specific-timedate#answer_424190

编辑：Ameer Hamza 2020-4-5

在 MATLAB Online 中打开

Try something like this

% example values
t = datetime('1/1/2020 00:00:00'):hours(8):datetime('31/1/2020 23:59:59');
val = rand(size(t));
t = timetable(t',val');
checkdate = datetime('1/15/2020 09:00:00');
idx = [find(t.Time < checkdate,1,'last') find(t.Time > checkdate,1,'first')];
values = t(idx,:);