Replacing elements in a vector

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L'O.G.
L'O.G. on 16 Jul 2022
Commented: L'O.G. on 17 Jul 2022
The values of an array match the index of elements in a vector. For example, the value of 5 in array1 below corresponds to whatever is in index 5 in vector1, i.e. the number 3 in this case. So how do I replace the value of the original number in array1 in the example by the number at the corresponding index in vector1? I realize this is a little confusing, so here's a mini example of what I want to do:
array1 = [1 2; 4 2; 5 5; 4 2];
vector1 = [2 1 1 4 3 4];
result = [2 1; 4 1; 3 3; 4 1];

Accepted Answer

Paul
Paul on 17 Jul 2022
array1 = [1 2; 4 2; 5 5; 4 2];
vector1 = [2 1 1 4 3 4];
result = [2 1; 4 1; 3 3; 4 1]
result = 4×2
2 1 4 1 3 3 4 1
result1 = vector1(array1)
result1 = 4×2
2 1 4 1 3 3 4 1
  3 Comments
Paul
Paul on 17 Jul 2022
vector1(array1) treats each entry of array1 as the linear index into vector1. The output takes the same shape as array1. It's the same as
array1 = [1 2; 4 2; 5 5; 4 2];
vector1 = [2 1 1 4 3 4];
reshape(vector1(array1(:)),size(array1))
ans = 4×2
2 1 4 1 3 3 4 1
L'O.G.
L'O.G. on 17 Jul 2022
Thank you. That is really neat!

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More Answers (1)

DGM
DGM on 16 Jul 2022
Your example isn't consistent. I'm assuming you want this:
A = [10 20; 30 40; 50 60];
idx = [2 1; 1 4; 3 3];
B = A.';
B = B(idx)
B = 3×2
20 10 10 40 30 30
  1 Comment
L'O.G.
L'O.G. on 16 Jul 2022
Thank you, but no, that's not what I want. I've edited my question to hopefully make it clearer.

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