;+ ;Purpose: Performs an intersection of two sets ;Parameters: l1,l2 sets(arrays) for which the intersection is ;calculated ; ;Returns: -1L on empty set, otherwise intersection of the two sets ; ;Notes: empty set is -1L ; all inputs must be empty set or arrays ; all outputs will be empty set or arrays ; Arrays must be of homogenous type ; ;- function ssl_set_intersection, l1, l2 if(size(l1, /n_dim) eq 0 && l1 eq -1L) then return, -1L if(size(l2, /n_dim) eq 0 && l2 eq -1L) then return, -1L if(size(l2, /n_dim) eq 0) then begin dprint, 'argument l2 to ssl_set_intersection should be of type array' return, -1L endif if(size(l1, /n_dim) eq 0) then begin dprint, 'argument l1 to ssl_set_intersection should be of type array' return, -1L endif ;concatenate and sort l3 = [l1, l2] l3 = l3[bsort(l3)] ;subtract id = where(l3 eq shift(l3, 1L), cnt) ;if its not an array ie empty intersection if cnt eq 0 then return, id ;permute l3 = l3[id] ;remove repeated elements and return s = l3[uniq(l3)] if(size(s, /n_dim) eq 0) then return, [s] return, s end