说明：  数据挖掘算法 dbscan 基于密度的聚类算法 它将簇定义为密度相连的点的最大集合，能够把具有足够高密度的区域划分为簇，并可在噪声的空间数据库中发现任意形状的聚类
(Data mining algorithms dbscan density-based clustering algorithm will cluster is defined as the density of points connected to the largest collection of regional division able to have a high enough density of clusters, clusters of arbitrary shape can be found in the noise of the spatial database)