question: protected static void quickSort ( Instances insts , int [ ] indices , int attidx , int left , int right ) { if ( left < right ) { int middle = partition ( insts , indices , attidx , left , right ) ; quickSort ( insts , indices , attidx , left , middle ) ; quickSort ( insts , indices , attidx , middle + 1 , right ) ; } }
target:  Sorts the instances according to the given attribute/dimension. The sorting is done on the master index array and not on the actual instances object.