MATLAB: Calculate the mean of two dimensions in a 3D array

arraymean

I have a 3D array and I want to calculate the mean of the first two dimensions along the 3rd dimension but I am getting the following error
"Assignment has more non-singleton rhs dimensions than non-singleton subscripts".
My code looks as follows
        MeanMatrix = zeros(1,1,30);
        ImageROI = data(50:55,100:105,:);
        for i=1:30
            MeanMatrix(:,:,i) = mean(ImageROI(:,:,i));       
        end

Best Answer

mean on a 2D matrix (your imageROI(:, :, i)) will return a vector. You can't assign a vector to a scalar (which is what MeanMatrix(:, :, i) is since it has 1 row and 1 column).
In any case, the loop is completely unnecessary:
MeanMatrix = mean(mean(ImageROI, 1), 2);
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