How to extract data from a 3D Array?
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I have a large (500x5x79039) 3D array, which is mostly filled with zeros. Now I want to extract the slices with content into a smaller array and save them. I’ve already tried the solution from this Article, but then I get the same page repeated multiple times, resulting in too many entries and duplicates.
Ideally, I would like to extract the pages exactly as they were saved, provided there is data on those pages.
4 个评论
Jonas
2024-4-18
so a slice is a 2d matrix for me, into which direction do you want to slice? if i understood correctly, you only want those 2d slices, in whch at least one entry is not zero?
Simon Schirk
2024-4-18
Harald
2024-4-18
Jonas inquired about the direction of indexing. In other words, you can get
a) a n x 5 x 79039 array with n < 500
b) a 500 x n x 79039 array with n < 5
c) a 500 x 5 x n array with n < 79039
Each can be done, but it would be great to know which of the three you are looking for.
Simon Schirk
2024-4-18
回答（1 个）
Use logical indexing -
%Sample data
p = 5;
q = 6;
r = 4;
y = rand(p,q,r)-1;
y(:, :, [2 r+1]) = zeros(p,q,2)
%Check if there is any non-zero element in a page
idx = any(y, [1 2])
%Use the (logical) index to get the corresponding data
out = y(:, :, idx)
2024-4-18
2024-4-18
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