Taking average of 3 rows from a matrix

I have a data that has 10 columns and 369 rows.

I would like to get average of every 3 rows so that the output will be 10 columns 123 rows.

So that I will be getting average of first three rows in the first row in the output spreadsheet.

Thank you in advance.

[Raghunandan V]

I think this is straightforward task. please try it yourself!

https://in.mathworks.com/matlabcentral/answers/6200-tutorial-how-to-ask-a-question-on-answers-and-get-a-fast-answer

Answer 1

[madhan ravi]

Simpler and faster than the other two:

[m,n]=size(A); % A is your matrix
Mean=reshape(mean(reshape(A,3,[])),[],n)

[Hyunjae Jeon]

I was checking google and Mathworks and found the reshape function. However, it was hard to apply it to my case. However, your comment on "n being number of column" clarified quite a lot.

Thank you

Answer 2

[KSSV]

A = rand(369,10) ; 
idx = repmat(3,1,369/3) ;
% arrange data 
B = mat2cell(A,idx) ; 
% get mean 
M = cellfun(@mean,B,'un',0) ;
M = cell2mat(M)

[Hyunjae Jeon]

Thank you for this comment!

Answer 3

[madhan ravi]

Using mat2cell() and cellfun() is slower than an explicit loop follow this instead:

[m,n]=size(A); % A is your matrix
U1=reshape(A.',n,3,m/3);
Uu=mean(permute(U1,[2 1 3])); 
Mean=squeeze(Uu).';