实现一个基于密度的聚类算法

public class DBScan {

    //设定一个距离分步阶梯 默认3为基础一级精度
    private static final int MAX_STEP = 3;

    public static final Long calcMostPoint(List list,int PRE) {
        long selid = 0;
        double begin_value = 0;
        Double[] plusArray = new Double[list.size()];

        //第一步 计算每个点与原始点的距离 存入 plusArray
        for (int i = 0; i < list.size(); i++) {
            HashMap map = (HashMap) list.get(i);
            if (i == 0) begin_value = new Double(map.get("value").toString());
            long id = new Long(map.get("id").toString());
            double value = new Double(map.get("value").toString());
            plusArray[i] = value - begin_value;
        }

        //第二步 计算距离上下限距离
        Double[] plusTemp = plusArray.clone();
        
        double plus_distance = plusTemp[plusTemp.length - 1] - plusTemp[0];

        //第三步 设置精度
        double precision = plus_distance / (MAX_STEP+PRE);

        //第四步 计算每个数以精度为半径 涵盖的数量
        Integer[] cn = new Integer[plusArray.length];

        for (int i = 0; i < plusArray.length; i++) {
            int count = 0;
            for (int j = 0; j < plusTemp.length; j++) {
                double d = Math.abs(plusArray[i] - plusTemp[j]);
                if (d < precision) count++;
            }
            cn[i] = count;
        }
        //第五步 计算 cn中最大的点 及位置
        Integer[] cntemp = cn.clone();
        
        int pos = getPos(cn, cntemp[cn.length - 1]);
        if (pos==-1) return null;
        //第六步 找出 list 中对应pos的id
        HashMap map = (HashMap) list.get(pos);
        selid = new Long(map.get("id").toString());
        return selid;
    }

    public static int findValue(Integer[] array, int key) {
        int left = 0; //数组第一个元素索引值
        int right = array.length - 1; //数组最后一个元素的索引值
        while (left <= right) {
            int mid = (left + right) / 2;
            if (array[mid] < key) {
                left = mid + 1;
                right = array.length;
                mid = (right - left) / 2;
            } else if (array[mid] > key) {
                right = mid - 1;
                left = 0;
                mid = (right - left) / 2;
            } else if (array[mid] == key) {
                return mid;
            }
        }
        return -1;
        //元素不在该数组中 返回 -1
    }
    public static int getPos(Integer[] array, int key) {
        for(int i=0;i<array.length;i++){
            if(array[i]==key) return i;
        }
        return -1;
    }
     


}