Method compare

JSAT/src/jsat/linear/vectorcollection/VPTree.java:271–275

(Pair<Double, Integer> o1, Pair<Double, Integer> o2)

        Collections.sort(S, new Comparator<Pair<Double, Integer>>() 
        {
            @Override
            public int compare(Pair<Double, Integer> o1, Pair<Double, Integer> o2)
            {
                return Double.compare(o1.getFirstItem(), o2.getFirstItem());
            }
        });
        int splitIndex = splitListIndex(S); 
        node.left_low = S.get(0).getFirstItem();