How to retime time series data every 15 minutes, or if it is not possible, to filter minutely data to 15-minutes data?

Hi! I have a question about how to retime time series data every 15 minutes. I have a time series data and I intend to retime it every 15 minutes. I use retime function, however it only provides retime in minutely for minute range. Is there any other way to retime time series data every 15 minutes?

Otherwise, I want to filter minutely data (from original data that I have retimed into minutely range) in every 15 minutes range. Is it possible to do that? I attach my original data, and here is the code I use for retime every minute:

%%Rainfall analysis
% for every minute
minutelyrainfall=table2timetable(rainanalysis);
minutelyrainfall=retime(minutelyrainfall,'minutely','linear');
minutelyrainfall=timetable2table(minutelyrainfall);

I would really appreciate for your help. Thank you very much in advance.

Answer 1

[Akira Agata]

To retime your data in every 15 minutes, first you should convert your data into 'timetable,' next create datetime vector (= resampling timing) and finally apply retime function. Here is an example.

load('rainanalysisdata.mat');

% Convert to timetable
rainanalysis.DatumUhrzeit = datetime(rainanalysis.DatumUhrzeit);
rainanalysis = table2timetable(rainanalysis);

% Create time vector (15 min duration)
t = rainanalysis.DatumUhrzeit(1);
startTime = datetime(t.Year,t.Month,t.Day,t.Hour,0,0);
time = (startTime:minutes(15):rainanalysis.DatumUhrzeit(end))';

% Resampling
rainanalysis2 = retime(rainanalysis,time,'linear');

[Kasih Ditaningtyas Sari Pratiwi]

Thank you so much, Akira Agata. I did not know that we can define start time and end time that way. Thanks, you're a life saver!