Calculate the mean of two dimensions in a 3D array

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Mar 2018-5-4

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https://ww2.mathworks.cn/matlabcentral/answers/399010-calculate-the-mean-of-two-dimensions-in-a-3d-array

评论： Rohit shaw 2021-10-10

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

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Answer 1

Guillaume 2018-5-4

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https://ww2.mathworks.cn/matlabcentral/answers/399010-calculate-the-mean-of-two-dimensions-in-a-3d-array#answer_318642

编辑：Guillaume 2018-5-4

在 MATLAB Online 中打开

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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Rohit shaw 2021-10-10

Hello, could you kindly tell me what would the command be if I have to use this command across 86 timesteps. I have a 3d array of 720x360x86. These are temperature values for the world.

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