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Robert
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Would be possible to calculate half hour average by using retime?

Asked by Robert
on 15 Aug 2017
Latest activity Edited by dpb
on 30 May 2019
Hello,
The current time steps allowed in retime https://www.mathworks.com/help/matlab/ref/retime.html are:
'yearly' One year
'quarterly' One quarter
'monthly' One month
'weekly' One week
'daily' One day
'hourly' One hour
'minutely' One minute
'secondly' One second
But would be possible to calculate half hour average? or other specific time step average (like 5, 10, 15 minutes...) beside the standard here mentioned?
Thanks.

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2 Answers

Answer by Teja Muppirala
on 15 Aug 2017
 Accepted Answer

Yes, there is an example a little bit down the in the documentation for RETIME , under this heading:
Interpolate Timetable Data to Arbitrary Times
I've copied the relevant sample code here:
%%Make sample data
Time = datetime({'2015-12-18 07:29:53';'2015-12-18 08:00:00';...
'2015-12-18 08:31:02';'2015-12-18 09:30:00'});
Temp = [37.3;41.9;45.7;39.8];
Pressure = [30.1;29.9;30.03;29.8];
TT1 = timetable(Time,Temp,Pressure)
%%Retime to 30 minute intervals
newTimes = [datetime('2015-12-18 07:30:00'):minutes(30):datetime('2015-12-18 09:30:00')];
TT2 = retime(TT1,newTimes,'linear')

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Show 1 older comment
Teja is correct. Just to expand a bit, those strings like 'yearly', 'quarterly', etc. are just conveniences for common uses. You can synchronize to any time vector you want as long as it's increasing. Doesn't even have to be regular.
Thank you, very appreciated Teja and Peter!
Update: In R2018a, there's a new syntax that makes this a bit easier:
tt = retime(tt,'regular',method,'TimeStep',minutes(30))

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Answer by Ohad Zivan on 5 Jul 2018
Edited by dpb
on 30 May 2019

From Matlab: Adjust Timetable Data to Regular Times Calculate the means over six-hour time intervals. Specify a regular time step using the 'regular' input argument and the 'TimeStep' name-value pair argument.
TT = retime(outdoors,'regular','mean','TimeStep',hours(6)); TT(1:5,:) ans=5×3 timetable Time Humidity TemperatureF PressureHg _________________ ______ __________ ________
2015-11-15 00:00:00 48.9 51.45 29.61
2015-11-15 06:00:00 48.9 51.45 29.6
2015-11-15 12:00:00 49.025 51.45 29.61
2015-11-15 18:00:00 48.9 51.225 29.607
2015-11-16 00:00:00 48.5 51.4 29.61

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