How to convert 3 hourly data into a 6 hourly data?

I have a 3D variable (time,latitude,longitude) every 3hourly (regular). I need to change this variable into 6 hourly by averaging (eg, 0hr and 3hr of old variable averaged, and stored as first time step in the new variable). In total my old variable has 56 time steps. How should I go about?

Answer 1

[Andrei Bobrov]

In R2016b

[m,n,k] = size(A);
t = hours(0:3:(k-1)*3);
Ar = reshape(A,m,[]);
TT = table2timetable(array2table(Ar),'RowTime',t(:));
T1 = retime(TT,TT.Time(1:2:end),'mean');
out = reshape(T1{:,:},[],n,k);

add:

[m,n,k] = size(A);
t = hours((0:m-1)*3)';
o1 = varfun(@mean,array2table([floor(t / hours(6)) + 1,reshape(A,m,[])]),...
                                                 'GroupingVariables','Var1');
out = reshape(o1{:,3:end},[],n,k);

[Arun Nair]

Hi! I use Matlab 2016a. So it comes as "Undefined function or variable 'table2timetable'".

[Andrei Bobrov]

Please see part 'add' in my answer.

[Arun Nair]

Thank you for your help!