Half hour data to monthly average

How do I calculate monthly average from daily half hour readings? Is there a specific function that can do this?

[Titania Markland]

I have my data in table format. So my data was imported from an excel file.

[Akira Agata]

Then, please use table2timetable function to convert it to timetable format.

[Titania Markland]

My data is in half hourly recordings, so I used the following code to convert to daily: t=reshape(t,48,[]); mean (t);

But after this part I think I am confused as what to do next to get it to monthly average?

[Akira Agata]

OK. Looking at your code, I think your data is stored in the N-by-1 numeric array. Then, I would recommend making a time stamp (N-by-1 datetime array), and convert them to timetable format.

The following sample code shows how to create time stamp (N-by-1 half-hourly datetime array), combine with data to make timetable, and calculate monthly average.

% Time stamp
Time = (datetime(2018,1,1):minutes(30):datetime(2019,1,1)-minutes(30))';

% Sample data
Data = 10+rand(numel(Time),1);

% Store the data as a timetable
TT = timetable(Time,Data);

% Calculate monthly average
TT2 = retime(TT,'monthly','mean');

The TT and TT2 looks like:

>> TT(1:4,:)
ans =
4×1 timetable
     Time        Data 
  __________    ______
  2018/01/01     10.06
  2018/01/01    10.682
  2018/01/01    10.042
  2018/01/01    10.071

>> TT2(1:4,:)
ans =
4×1 timetable
     Time        Data 
  __________    ______
  2018/01/01    10.498
  2018/02/01    10.509
  2018/03/01    10.508
  2018/04/01    10.491

Answer 1

[Akira Agata]

If your data is stored in timetable format, you can do that simply using retime function, like:

newTimeTable = retime(yourTimeTable,'monthly','mean');

Answer 2

[Andrei Bobrov]

d = 10*rand(275,48) - 5;% let d - your data -> one row - one day
date1 = datetime(2018,2,20 + (0:size(d,1)-1)') ; % Enter date of first day, e.g. - 20-Feb-2018
TT = array2timetable(mean(d,2),'RowTimes',date1);
% Further, as Akira wrote:
TTout = retime(TT,'monthly','mean');