how to convert three dimension daily data into monthly mean?

 I have three dimension daily data contaning (station, year, day)(387x2x365), i need to convert into monthly mean for each year (387x2x12).
current code is attached below, thank you.
load('prec_aphrodite.mat')
prec=prec_aphrodite;
for i=1:2
    for ii=1:387
        days=[31 28 31 30 31 30 31 31 30 31 30 31] 
        dd=0;
        for mm=1:12
            mmprec=prec((dd+1):days(mm)),3);
            for ddd=1:days(mm)
            prec_aph_mm(ii,i,mm)=nanmean(prec(((dd+1):dd+days(mm)),3))
            dd=dd+days(mm)
        end
    end
end

Answer 1

[Akira Agata]

Let me try it step-by-step:

% Load the data
load('prec_aphrodite.mat');

% Reshape the data to 730(day)-by-387(site) array
data_year1 = squeeze(prec_aphrodite(:,1,:))';
data_year2 = squeeze(prec_aphrodite(:,2,:))';
Data = [data_year1; data_year2];

% Assuming the first day is 2001/1/1
Time = datetime(2001,1,1):days(1):datetime(2002,12,31);
Time = Time';

% Create timetable by combining 'Time' and 'Data'
TT = table2timetable([table(Time),array2table(Data)]);

% Calculate monthly mean value for each site
TT2 = retime(TT,'monthly','mean');

The result is:

>> TT2
ans =
24×387 timetable
     Time        Data1      Data2 ...
  __________    _______    _______
  2001/01/01    0.93232     1.0593 ...
  2001/02/01     2.3482     2.4687 ...
  2001/03/01     2.3196     2.1202 ...
  2001/04/01    0.75275    0.63212 ...
  ...           ...        ...

[shanka sharma]

thankyou very much!