stelios loizidis - 2023-04-17T09:52:59+00:00
Question: Select values based on datetime
Hello, I have the matrix Values (1X2100) and the corresponding DateTime matrix with datetime data (1x2100 datetime). The values in Values matrix are hourly. I want to categorize the values of the Values table into 3 categories. I wrote the following codes for categorization, [k1,i1]=find(Values<0); [k2,i2]=find(0<=Values & Values<=80; [k3,i3]=find(80
Expert Answer
Kshitij Singh answered .
2025-11-20
The very first thing you should do is put your data and timestamps in a timetable.
Once you do that, use retime to create a daily timetable, using your own custom aggregation function that returns 1, 2, or 3 according to your rules ("the same dates that exist in Cat_Time_1 and Cat_Time_2 stay in Cat_Time_1 and leave Cat_Time_2 ...", which I don't really understand but you should be able to write that function.
Now you have a list of days and what category they are in. Use dateshift on your original timetable to add a new variable that is the day timetamp, use join to combine that with the daily timetable, and select data from tyhat using the category number.
The custom function aside, this is just a few lines of code. No loops needed.
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