Given two arrays A and B, how to get B values which are the closest to A.

Suppose I have two arrays ordered in an ascending order, i.e.:

 A = [1 5 7], B = [1 2 3 6 9 10]

I would like to create from B a new vector B', which contains only the closest values to A values (one for each).

I also need the indexes. So, in my example I would like to get:

 B' = [1 6 9]. Idx = [1 4 5]

Note that the third value is 9. Indeed 6 is closer to 7 but it is already 'taken' since it is close to 4.

Any idea for a suitable code?

Note: my true arrays are much larger and contain real (not int) values

Thanks!

Answer 1

[the cyclist]

Here is a very straightforward way to get your values of B_prime and Idx.

A = [1 5 7];
B = [1 2 3 6 9 10];

NA = length(A);

B_prime = zeros(1,NA);
B_orig = B;

for n = 1:NA
    [~, j] = min(abs(A(n)-B));
    B_prime(n) = B(j);
    B(j) = [];
end

[~,Idx] = ismember(B_prime,B_orig);

I expect this code will run into problems if the values in B are not unique (but I did not test that for you).

After admittedly very little thought, I could not think of any easy way to vectorize this, given your requirement of not replicating elements of B.

[JazzMusic]

It worked. Thank you!