Extracting a vector from a 3d array

Question

Graham 2014-4-29

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https://ww2.mathworks.cn/matlabcentral/answers/127616-extracting-a-vector-from-a-3d-array

评论： the cyclist 2023-10-19

Hi, I have a 3d array called 'A' of size (l,m,n)=12x15x3648.

I want to extract all 3648 values for a given index (l,m) as a single column vector. Doing A(7,8,:) for example outputs many individual answers and is not useful. I would like them in a vector which is 3648 elements long.

Any help is appreciated. Thanks.

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Answer 1

the cyclist 2014-4-29

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https://ww2.mathworks.cn/matlabcentral/answers/127616-extracting-a-vector-from-a-3d-array#answer_135021

编辑：the cyclist 2014-4-29

在 MATLAB Online 中打开

Two alternatives:

squeeze(A(7,8,:))

and

permute(A(7,8,:),[3 1 2])

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Gianmarco Venditti 2023-10-19

Why doing something like:

X = A(:,7,8) you have vector ( a one index object)

while

X = A(7,8,:) produce a 4-D tensor? (Still have 4 index)

the cyclist 2023-10-19

Can you upload an example of an array A where you see that happening? You can attach a MAT file using the paper clip icon in the INSERT section of the toolbar.

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