Hi,

I have a matrix like this, two columns: a, b

 a b  c1 21  c2 19  c2 20  c2 20  c4 25  c5 18  c5 18
how to prepare a new matrix removing the rows with repeated units in b
columns, like there are two 20 and two 18 in b column (others are unique in
b col).  I wanna a pure matrix with one 20 and one 18.

Thanks a lot!

Yan

	[[alternative HTML version deleted]]

