Keep only certains rows (continuation)

This is a follow-up question of this one.

I have the following matrix:

A = [1 2 2;
     1 3 3;
     1 1 2;
     2 9 3;
     2 4 3;
     2 0 2]

which has an index (1, 2, etc...) in the first column, and the relevant information in the 2nd column; as well as another third column that contains more information.

I would like to reduce this matrix so that only 1 row stays with the same index: the row with the minimum relevant value (2nd column). The third column values of the remaining rows should be kept.

It should look like this:

B = [1 1 2;
     2 0 2]

the rest of the rows should not appear.

Is there an easy way I could do that?

Answer 1

[Roger Stafford]

A variation on Matt's method which takes advantage of the fact that column 1 in B is already sorted.

 B = sortrows(A,[1,2]);
 B = B(find([true;diff(B(:,1))>0]),:);

Answer 2

[Matt J]

   B=sortrows(A,[1,2]);

   [~,idx]=unique(B(:,1),'stable'); 

   B=B(idx,:)