How to select a repetitive range?

Hi all,

I have a data from 1 to 8760 representing the hours of the year. I want to select for instance 11 to 17 and repeat it every 24 hours (selecting the same range in the next day, the value will be added by 24 so that it jumps to 11 o'clock in the second day and so on). How should I do that?

Thanks

[dpb]

Instead, convert to datetime or duration and use time intervals. timetable has specific methods to help; you can also then group by ranges to process without actually having to select and create temporary copies of the data.

[Wolfgang McCormack]

@dpb well that's more lines of code to get than done since I have to create a conditional time selection for hours. I wish matlab could handle that automatically in timetables.

[Peter Perkins]

Actually, this is super easy using a timetable:

>> hourly = timetable(datetime(2021,1,1,0:8759,0,0)',rand(8760,1));
>> t = datetime(2021,1,1:365) + hours(11:17)'; % implicit expansion: row + column
>> hourly_11_17 = hourly(t,:);
>> head(hourly_11_17)
ans =
  8×1 timetable
            Time              Var1  
    ____________________    ________
    01-Jan-2021 11:00:00     0.61605
    01-Jan-2021 12:00:00     0.89185
    01-Jan-2021 13:00:00     0.71641
    01-Jan-2021 14:00:00     0.86522
    01-Jan-2021 15:00:00     0.83825
    01-Jan-2021 16:00:00    0.019567
    01-Jan-2021 17:00:00     0.33124
    02-Jan-2021 11:00:00     0.38599

Answer 1

[Walter Roberson]

data_day = reshape(YourData, 24, [], size(YourData,2));
data_day(11:17, :, :)

You could reshape() that to [], size(data_day,3) if you want to push the chunks back together again, but I suspect having it by hour will be more useful.

Or

idx = (11:17).' + (0:24:size(YourData,1)-1);
selected_data = YourData(idx,:)