Replacing several values in multidimensional array simultaneously

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David Hoffmeyer
David Hoffmeyer 2020-9-14
编辑： Bruno Luong 2020-9-14
I have a multidimensional array, e.g.
A(:,:,1) = [1 2 3 ; 4 5 6];
A(:,:,2) = [7 8 9 ; 10 11 12];
I want to replace several of the values in this array with the same value simultaneously. Specifically I want to do this column-wise, the result should be e.g.
A(:,2,1) = [-1 ; -2];
A(:,3,2) = [-1 ; -2];
yielding
A(:,:,1) = [1 -1 3 ; 4 5 -1];
A(:,:,2) = [7 -2 9 ; 10 11 -2];
I attempted this by
B = [2 3]; C = [1 2];
A(:,B,C) = [-1 ; -2];
but it does not give the wanted result.
Any idea on how to do this without performing a for-loop?

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采纳的回答

Bruno Luong
Bruno Luong 2020-9-14
编辑：Bruno Luong 2020-9-14
A(:,:,1) = [1 2 3 ; 4 5 6];
A(:,:,2) = [7 8 9 ; 10 11 12];
s = size(A);
A(:, sub2ind(s(2:3),[2 3],[1 2])) = 0 % = [0 0; 0 0]
  2 个评论
David Hoffmeyer
David Hoffmeyer 2020-9-14
编辑：David Hoffmeyer 2020-9-14
Thanks for your input. However, I have not been precise enough in my question. I need to replace a number of columns in the array with a column containing non-identical values (see the edited question), and not just 0. In that case your proposal does not work. Can you alter it correspondingly?
Bruno Luong
Bruno Luong 2020-9-14
编辑：Bruno Luong 2020-9-14
Just replace the RHS as I hint in my answer with "% = [0 0; 0 0]"
A(:, sub2ind(s(2:3),[2 3],[1 2])) = [[-1;-2], [-1;-2]]

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