# Add elements of array A to array B and ensure there is no repeated element in B?

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Xiaohan Du on 10 Jul 2018
Commented: Xiaohan Du on 10 Jul 2018
Hi all,
If I have arrays A and B, and I'd like to add elements of array A into array B, during this process, B is actively checked to ensure there is no repeated elements in B, how can I do it?
Many thanks!
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Xiaohan Du on 10 Jul 2018
For example:
A = [2 3 4]; % before adding
B = [5 4 3 1 3]; % add B to A, has to be an iterative check
% because in my code elements of B is generated iteratively,
% not all at once.
A_output = [2 3 4 5 1]; % after adding, no repeated element

KSSV on 10 Jul 2018
A = rand(10,1) ;
B = rand(10,1) ;
%%check for B
[C,ia,ib] = unique(B) ;
if length(C)==length(B)
fprintf('B has no repeated elements\n') ;
R = A+C ;
else
fprintf('B has repeated elements\n') ;
end
##### 1 CommentShowHide None
Xiaohan Du on 10 Jul 2018
I meant when adding elements of B into A, check if A has repeated elements. But anyway, this allows to find out if A has repeated elements.
So now there is the problem: if there is repeated element in A, how to remove it and continue to move and check?

Guillaume on 10 Jul 2018
B = unique([B, A]); %assuming B and A are row vectors.
If you want to preserve the original ordering of elements:
B = unique([B, A], 'stable');