Combining two vectors into a new one

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Irem Sara on 11 Mar 2022
Commented: Irem Sara on 11 Mar 2022
Hi,
I am working on a dynamic programming problem and I now have two equal-sized vectors, say vector A and B. I am trying to generate a new vector that starts with the first element of vector B, then finds the closest value in A and takes it's index value, then records the value corresponding to this index in B. I want to make a loop and cover all values in my vector B. Is there a way to code this? (Vector A and B won't have the exact same values unfortunately, so the code will need to find the closest element's index)
Thanks!

Johan on 11 Mar 2022
I don't know if there is a builtin function to do that but you can achieve using translation, logical condition and find:
A = randi(10,5,1);
B = randi(10,5,1);
% compute difference of each element of B with each element of A
abs(B'-A)
ans = 5×5
1 0 3 4 3 2 1 2 3 2 4 3 0 1 0 5 4 1 0 1 4 3 0 1 0
% minimum difference value
min(abs(B'-A))
ans = 1×5
1 0 0 0 0
% Create a logical mask of the position of the minimum difference
1 1 0 0 0 0 0 0 0 0 0 0 1 0 1 0 0 0 1 0 0 0 1 0 1
%use find to get the index and rescale the index using the width of the array
%Equal distance increase the size of C compared to A and B
C = 7×1
1 1 3 5 4 3 5
Irem Sara on 11 Mar 2022
This is exactly what I was looking for- thank you so much!

KSSV on 11 Mar 2022
A = rand(3) ;
B = rand(2) ;
idx = knnsearch(B(:),A(:))
Also have a look on ismember, ismembertol.