How to index array with an array?

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xiaojuezi
xiaojuezi 2021-12-8
评论： xiaojuezi 2021-12-8
Hi I want to index an element in an array. The array u can be 1D, 2D or 3D, and I have an index id which is 1D, 2D or 3D. I'm currently doing:
u(id) = val;
This works fine in the 1D case. However, for 2D cases, where id = [row,column], this line doesn't set the 2D array correctly. For example:
u = [0 0 0;
0 0 0;
0 0 0];
% Access element at row 2, column 1
id = [2,1]
u(id) = 1; % Not always setting the desired element
Similarly in 3D, id = [widthId, heightId, depthId].
Is there a way to solve this?
Thank you very much!
  1 个评论
James Tursa
James Tursa 2021-12-8
Please give a small numerical example of exactly how your 2D and 3D indexes are stored.

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Stephen23
Stephen23 2021-12-8
编辑：Stephen23 2021-12-8
Ran in:
u = [11,12,13;21,22,23;31,32,33]
u = 3×3
11 12 13 21 22 23 31 32 33
% Access element at row 2, column 1
id = [2,1]
id = 1×2
2 1
ic = num2cell(id);
u(ic{:})
ans = 21
https://www.mathworks.com/help/matlab/matlab_prog/comma-separated-lists.html
https://www.mathworks.com/matlabcentral/answers/320713-how-to-operate-on-comma-separated-lists

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