How I can extract data from a vector based on index

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I have an index and a vector I would like to have data from the vector which is not in the index!For example
A=[5 3 7 8 89 6]
index=[2 3 4 5]
Now I want to have B as my answer B=[5 6] Thanks!

Accepted Answer

Roger Stafford
Roger Stafford on 3 Jun 2016
Edited: Roger Stafford on 3 Jun 2016
B = A(setdiff((1:length(A)).,index(:)));
or if you're sure A and index are row vectors just
B = A(setdiff(1:length(A),index));

More Answers (2)

Stephen23
Stephen23 on 11 Apr 2022
A simple and efficient approach:
A = [5,3,7,8,89,6];
index = [2,3,4,5];
B = A;
B(index) = []
B = 1×2
5 6

Johanna
Johanna on 21 Feb 2022
I looking for the opposite command of setdiff. That is, taking the example from above, I want the answer to be B=[3 7 8 89].
In particular I'm actually looking for the mean of the values mentioned in my index vector. I tried mean(A(index)), however, this does not work.
I guess it has to be something like mean(A(setequal(1:length(A),index))), however, setequal does not exist. Thanks!

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