Intersection of two matrices based on 1st column

I have two matrices of with different number of columns but same number of rows (large data sets). Here is an exapmle.

A = [1 2 3; 4 5 6; 6 8 9];

B = [1 2 3 5; 4 6 7 8 ; 9 10 11 12];

I am looking to compare A and B on the basis of values in 1st column only and get an out put of the rows which are not common based on this criteria. Hence,

C = [ 9 10 11 12];

I have tried intersect with rows option but it needs same number of columns and secondly i dont have same values throught two rows (but only in the1st column) to work it properly.

[Yasir Zahoor]

Just to add, I would like to keep the order of the resultant rows intact.

Answer 1

[Guillaume]

[~, rowstokeep] = setdiff(B(:, 1), A(:, 1));  %get index of rows in B whose 1st column is not in 1st column of A
C = B(rowstokeep, :)

[Guillaume]

Just to add, I would like to keep the order of the resultant rows intact.

Use the 'stable' option of setdiff, then.

[Yasir Zahoor]

thanx