how to take average of each column of matrices

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chan 2021-11-30

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评论： Stephen23 2021-12-3

A = randi(9,[6 3 6]);

U = 3:5;

% do it with a loop

M = zeros(size(A,1),size(A,2),numel(U));

for k = 1:length(U)

M(:,:,k) = A(U(k),1,2) * A(:,:,U(k));

end

%Here i have 3 matrices i.e. M(:,:,1),M(:,:.2),M(:,:,3).

Could someone suggest me a hint on how to take the average of each column of the three matrices. result will be a 6*3 matrix

"sendcnt" can be 3/4/5

when i do M/sendcnt then each cell of the matrix is divided by sendcnt which is not right.

what i want is (1st column of 1st matrix+1st column of 2nd matrix+1st column of 3rd matrix)/sendcnt

similarly for the other 2nd and 3rd column.

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Stephen23 2021-12-3

"i want mean for column of the 3D matrix. it will be 6*3 matrix"

The mean along column of a 6x3x6 array will return a 6x1x6 array.

I suspect that you might want the mean along the third dimension (aka "page"):

https://www.mathworks.com/help/matlab/math/multidimensional-arrays.html

The mean along each "page" will return a 6x3(x1) array.

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Answer 1

Rik 2021-11-30

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在 MATLAB Online 中打开

It sounds like you want something like this:

A = randi(9,[6 3 6]);
U = 3:5;
% do it with a loop
M = zeros(size(A,1),size(A,2),numel(U));
for k = 1:length(U)
    M(:,:,k) = A(U(k),1,2) * A(:,:,U(k));
end
data=mean(M,2); %apply mean over the second dimension (columns)
squeeze(data) % reshape the nx1xm to nxm
ans = 6×3
   45.3333   25.0000    4.3333
   18.6667   13.3333    4.3333
   21.3333   16.6667    4.0000
   58.6667   26.6667    4.6667
   40.0000   26.6667    6.0000
   18.6667   18.3333    5.0000

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chan 2021-12-3

i want mean for column of the 3D matrix. it will be 6*3 matrix

Rik 2021-12-3

That is what mean(M,2) does, however, the result is not 6*3 but 6*1*3. The reason is that you only have 1 column left if you calculate the average of the columns.

Can you give an example of input and expected output?

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