Indexing arrays of varying dimensionality.

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Lionel Pöffel
Lionel Pöffel el 2 de Mzo. de 2021
Editada: Stephen23 el 23 de Feb. de 2022
I have to handle arrays of varying dimensionality in one loop, and I have to index individual elements of those arrays.
From what I have seen in the general help, the only solution seems to be to do a stupid and unflexible switch-case-like approach, such as
sz=size(arr);
switch length(sz)
case 1:
ind1=calc_ind(1);
elem_val=arr(ind1);
case 2:
ind1=calc_ind(1);
ind2=calc_ind(2);
elem_val=arr(ind1,ind2);
case 3:
ind1=calc_ind(1);
ind1=calc_ind(2);
ind3=calc_ind(3);
elem_val=arr(ind1,ind2,ind3);
end
This makes it impossible to handle arrays of arbitrary dimensionality and is also very stupid and repetitive.
Using linear indices doesn't seem to help, because also sub2ind() needs different calls for each dimensionality.
Is there not an easier solution. like
sz=size(arr);
for d=1:length(sz)
ind_arr(d)=calc_index(d);
end
LinIndex=sub2ind(sz,ind_arr);
elem_val=arr(LinIndex);

Respuesta aceptada

Stephen23
Stephen23 el 2 de Mzo. de 2021
Editada: Stephen23 el 23 de Feb. de 2022
  1 comentario
Stephen23
Stephen23 el 2 de Mzo. de 2021
Complete working example:
arr = rand(7,6,5,4,3,2);
idx = [5,3,4,4,1,1];
tmp = num2cell(idx);
x = arr(tmp{:})
x = 0.2769
y = arr(5,3,4,4,1,1)
y = 0.2769

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Más respuestas (1)

Lionel Pöffel
Lionel Pöffel el 3 de Mzo. de 2021
Thanks, that works beautifully!

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