compare two matrix and for the elements in common find the minimum difference between specif fields

Hi all,

I've two matrices A and B. In the 1st columns of both, there are non unique numbers representing the serial code, e.g. 01 and 02 in my case. Only in the row intervals in A and B having the same serial code, I would find the index of closest value in the 2nd column of B compared with the 2nd column in A. Then, I would to extract from the 3th column of B the value defined by the index and store it in A.

A = [01 105  6;
     01 203 12;
     02  99  6;
     02 306 15]

B = [01   0  5;
     01 100 25;
     01 200 55;
     01 300 75;
     02   0  0;
     02 100 20;
     02 200 30;
     02 300 40;
     02 400 50]

The following doesn't work correctly...

out=A;
 for k=1:size(A,1)
  ii=ismember(B(:,1),A(k,1));
   [~,idx]=min(abs(A(k,2)-B(ii,2)));
   out(k,4)=B(idx,3);
  end
 out

As result, I would a matrix C as:

C = [01 105  6 25;
     01 203 12 55;
     02  99  6 20;
     02 306 15 40]

Any suggestion to do this?

Answer 1

[the cyclist]

Here is a pretty obfuscated solution:

[~,idx] = min(abs(1./((B(:,1)'==A(:,1))) .* (B(:,2)'-A(:,2))),[],2);
C = [A,B(idx,3)];

[gianluca]

Thanks but it give me an error:

Error using  == 
Matrix dimensions must agree.

[the cyclist]

That syntax will work with more recent versions of MATLAB. Try this instead:

[~,idx] = min(abs(1./((bsxfun(@eq,B(:,1)',A(:,1)))) .* (B(:,2)'-A(:,2))),[],2);
C = [A,B(idx,3)];