Averaging specific rows and specific columns in N by N matrix

Question

Abdulhakim Alezzi 2023-1-9

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https://ww2.mathworks.cn/matlabcentral/answers/1891032-averaging-specific-rows-and-specific-columns-in-n-by-n-matrix

评论： Mathieu NOE 2023-1-11

采纳的回答： Mathieu NOE

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hI friends,

I am trying to do averging for specfic rows with specific columns in C=19*19 matrix to have a final matrix of 5*5.

I am using the following code :

Y=mean (C([3:5 10:11 16:17, 12:13 19, 1 7, 2 6 8, 14:15],[3:5 10:11 16:17, 12:13 19, 1 7, 2 6 8, 14:15]));

But the output matrix is 1*17.

Any help will be appreciated.

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Answer 1

Mathieu NOE 2023-1-10

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hello

you need somehow to split your 5 domains into separate arrays (like a cell array as below)

then you can perform a for loop on each submatrix

try this

C = rand(19,19);
ind = [{[3:5 10:11 16:17]}; {[12:13 19]}; {[1 7]}; {[2 6 8]}; {14:15}];
for ci = 1:numel(ind) % row
    for cj = 1:numel(ind) % col
        ind_r = ind{ci};
        ind_c = ind{cj};
        Y(ci,cj)=mean(C(ind_r,ind_c),'all');
    end
end