A method of constructing a mask for use in semiconductor device manufacturing is disclosed. A first shape that is related to mask construction is selected from a set of shapes. A second shape related to the mask construction is selected from the set of shapes. The first shape and the second shape are represented using a first shape vector and a second shape vector, respectively. A cluster is formed that includes the first shape and the second shape when the first shape vector and the second shape vector are within a selected criterion.