▁data ▁set . ▁ ▁Ext ensions ▁OP T IC S - OF ▁is ▁an ▁out lier ▁detection ▁algorithm ▁based ▁on ▁OP T IC S . ▁The ▁main ▁use ▁is ▁the ▁extra ction ▁of ▁out liers ▁from ▁an ▁existing ▁run ▁of ▁OP T IC S ▁at ▁low ▁cost ▁compared ▁to ▁using ▁a ▁different ▁out lier ▁detection ▁method . ▁The ▁better ▁known ▁version ▁L OF ▁is ▁based ▁on ▁the ▁same ▁concepts . ▁ ▁De Li - C lu , ▁D ens ity - Link - Cl ust ering ▁comb ines ▁ideas ▁from ▁single - link age ▁clust ering ▁and ▁OP T IC S , ▁elimin ating ▁the ▁ ▁parameter ▁and ▁offering ▁performance ▁improvements ▁over ▁OP T IC S . ▁ ▁Hi SC ▁is ▁a ▁hier arch ical ▁sub space ▁clust ering ▁( axis - parallel ) ▁method ▁based ▁on ▁OP T IC S . ▁ ▁Hi CO ▁is ▁a ▁hier arch ical ▁correlation ▁clust ering ▁algorithm ▁based ▁on ▁OP T IC S . ▁ ▁Di SH ▁is ▁an ▁improvement ▁over ▁Hi SC ▁that ▁can ▁find ▁more ▁complex ▁hier arch ies . ▁ ▁F OPT IC S ▁is ▁a ▁faster ▁implementation ▁using ▁random ▁pro jections . ▁ ▁H DB SC AN * ▁is ▁based ▁on ▁a ▁ref in ement ▁of ▁DB SC AN , ▁ex cluding ▁border - points ▁from ▁the ▁clusters ▁and ▁thus ▁following ▁more ▁strictly ▁the ▁basic ▁definition ▁of ▁density - level s ▁by ▁Hart igan . ▁ ▁Av ail ability ▁Java ▁implementations ▁of ▁OP T IC S , ▁OP T IC S -