Hi, I am currently testing the new distance() function under development. Thank you again for this new feature. I am focusing on the pairwise case where both matrices X and Y are given. Here is a toy example: <hansl> clear set verbose off matrix X = {1, 2; 3, 4} matrix Y = {1, 2; 0, 3} expected_distances = {0, 2; 4, 4} matrix actual = distance(X, "manhattan", Y) print actual print expected_distances actual (4 x 1) 0 2 4 4 expected_distances (2 x 2) 0 2 4 4 </hansl> The matrix expected_distances is replicating sklearn's behavior. As you can see, sklearn returns a matrix instead of a column vector. I am not sure what the standard is and/ or other software packages return. I just want to mention this. Being in line with some widely-applied "standard" is useful, I would say. I also think that the matrix version is easier to read - but that might be a matter of taste ;-) Also, the help text does not say anything on the return dimension in case both matrices X and Y are given. Artur