How to split the data wrt date in 3 dimensions array

Hi all, I have data starts from 1/Jan/1979 to 31/Dec/2019 year with 3 dimensions array is 10x10x14975. I also have the 3 periods = [1979 1979 ; 1980 1999 ; 2000 2019]. So I want to split the data only with respect to period 2 and 3, then to simulate the mean for that each period. Please help me. Thanks you.

Answer 1

[Andrei Bobrov]

ARR = randi(10,10,10,14975); % Your 3d array 10x10x14975 

a = datenum([1979 1 1;2019 12 31]);
yy = [1979 1 1;1980 1 1;2000 1 1];
[yyyy,mm,dd] = datevec((a(1):a(2))');
n = numel(dd);
ii = cumsum(ismember([yyyy,mm,dd],yy,'rows'));
out = accumarray(ii,(1:n)',[],@(x){ARR(:,:,x)});

Answer 2

[Nam]

Thanks Andrei Bobrov a lot. It is what I need.