How to correctly store and access data in a 4D array?

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Luqman Saleem
Luqman Saleem 2024-3-4
编辑： Stephen23 2024-3-4
Suppose I store some 2-by-2 matrices in a 4D array as following
data = zeros(10,5,2,2);
for i = 1:10
for j = 1:5
a = [i+j, 0;
i-j, 0];
data(i,j,:,:) = a;
end
end
later, I want to acess these 2-by-2 matrices. How can I correctly access them? Is the following way a correct way?
i = 2;
j = 5;
matrix = reshape( data(i,j,:,:), 2, 2)
I have tested this method for several i and j. it seems to work, but I am not sure if this always gives correct result.
  2 个评论
Stephen23
Stephen23 2024-3-4
编辑：Stephen23 2024-3-4
"Is the following way a correct way?"
It seems to be. If you permute the dimensions of that matrix then you would not need to RESHAPE all the time.
Note: explicit RESHAPE is better than uncontrolled SQUEEZE.

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采纳的回答

Hassaan
Hassaan 2024-3-4
编辑：Hassaan 2024-3-4
Ran in:
It can be and other way could be:
% Initialize a 4D array to store 2-by-2 matrices
data = zeros(10,5,2,2);
% Fill the array with 2-by-2 matrices
for i = 1:10
for j = 1:5
a = [i+j, 0;
i-j, 0];
data(i,j,:,:) = a;
end
end
% Access a specific 2-by-2 matrix without reshape
i = 2;
j = 5;
matrix = squeeze(data(i,j,:,:));
% Display the accessed matrix
disp(matrix);
7 0 -3 0
-----------------------------------------------------------------------------------------------------------------------------------------------------
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