Calculate the mean of two dimensions in a 3D array

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Mar 2018 年 5 月 4 日

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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採用された回答

Guillaume 2018 年 5 月 4 日

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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その他の回答 (1 件)

KL 2018 年 5 月 4 日

If you want the mean of all rows in every page(3rd dimension)
mean(ImageROI,1)
for columns in every page
mean(ImageROI,2)
and mean of pages,
mean(ImageROI,3)
if you're looking to calculate the mean of all elements in a page, mean2 would be something
mean2(ImageROI(:,:,pageNo)) %with a loop
without a loop, probably with reshape,
mean(reshape(ImageROI,[],size(ImageROI,2),1))

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