Calculate standard deviation of 5-minute for different time interval

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Ann
Ann 2021-1-6
评论： Mathieu NOE 2021-1-7
Hi, everyone.
Here I attached my observations data on 1-31 of January 2014 for 24 hours from different transmitter (PRN) . By this excel, the 1-minute average for VTEC, S4 and Sigma for each 31 days already coded as below.
My problem now is, how can I find shortcut to calculate the standard deviation with the time interval of 5 min from the dataTT1min ? Should I reshape the column and row by separating it daily? Or how can I do by using for loop function?
Example:
TimeStamp VTEC S4 Sigma
'01-01-14 00:05' 15.0339395135249 0.0532669682730302 0.0447520000000000
'01-01-14 00:06' 10.1911139214755 0.0471003695720050 0.0373840000000000
'01-01-14 00:07' 12.1389652170293 0.0716977380449952 0.0451266666666667
'01-01-14 00:08' NaN NaN NaN
'01-01-14 00:09' 15.6912781124977 0.0547043336042455 0.0438950000000000
'01-01-14 00:10' 3.85456568208492 0.0395215802440296 0.0354220000000000
'01-01-14 00:11' 3.0019381831895 0.0687632803996655 0.0408106666666667
'01-01-14 00:12' 15.6748996657200 0.0903593103110256 0.0454846000000000
'01-01-14 00:13' NaN NaN NaN
'01-01-14 00:14' 10.5174985112160 0.0448554406539539 0.0380092500000000
Then, expected to get std VTEC from 00:05-00:09 and 00:10-00:14.Later will resulting only 288 std for one day (approx 8,928 std for January).
Any assistance would be highly appreciated.
data = readtable("Book_Jan.xlsx");
%_______________Read data_______________%
%___Convert DAY and TIME into durations___%
data.DAY = days(data.DAY);
data.TIME = days(data.TIME);
%___Create a datetime___%
data.TimeStamp = datetime(2014,01,01) + data.DAY-1 + data.TIME;
data.TimeStamp.Format = "MM-dd-yy HH:mm";
%___Convert the table to a timetable___%
dataTT = table2timetable(data,"RowTimes","TimeStamp");
%___Use retime to average the data into 1 minute increments___%
dataTT1min = retime(dataTT(:,["VTEC" "S4" "Sigma"]),"minutely","mean");

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Mathieu NOE
Mathieu NOE 2021-1-6
hello Ann
I slightly modified your code so the data are resampled with time increment of 5 minutes (or whatever value you're looking for)
hope it helps !
data = readtable("Book_Jan.xlsx");
%_______________Read data_______________%
%___Convert DAY and TIME into durations___%
data.DAY = days(data.DAY);
data.TIME = days(data.TIME);
%___Create a datetime___%
data.TimeStamp = datetime(2014,01,01) + data.DAY-1 + data.TIME;
data.TimeStamp.Format = "MM-dd-yy HH:mm";
%___Convert the table to a timetable___%
dataTT = table2timetable(data,"RowTimes","TimeStamp");
%% MN : % round time to nearest 5 min and take unique values only
tt = data.TimeStamp;
tt.Minute = 5 * floor(tt.Minute/5); % here ! 5 means 5 mins resampling
tt.Second = 0;
NEWTIMESTEP = unique(tt);
%___Use retime to average the data into 5 minute increments___%
dataTT5min = retime(dataTT(:,["VTEC" "S4" "Sigma"]),NEWTIMESTEP);
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Ann
Ann 2021-1-6
Maybe this explanation can help you for a better understanding.
https://www.mathworks.com/matlabcentral/answers/522204-how-can-i-retime-my-timetable-with-a-10days-timestep#answer_429566
Mathieu NOE
Mathieu NOE 2021-1-7
Hi
tx for the link
It was simply lacking the ,"regular","mean" portion of the code !

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