车辆监控项目，记录车辆GPS定位数据，我们在检测浙江省高速道路的时候，GPS热力图显示，结果变成这样了，如图：

MongoDB里，存储数据的格式是这样滴
{

"_id" : ObjectId("593e58b8d1eece32080d6632"), "x" : 121.494230074275, "y" : 29.6998736880818

}

通过查询后，返回json格式是这样的：

{"lng":"121.98826732480999624","lat":"29.88628748150999925","count":1},{"lng":"122.00810540175000085","lat":"29.82699952501900142","count":1},{"lng":"122.00148151521000273","lat":"29.82556419141700133","count":1},{"lng":"122.09566082377000384","lat":"29.86581727309599898","count":1},{"lng":"121.99538599286999840","lat":"29.82299558164600128","count":1},{"lng":"121.98481996031999586","lat":"29.81670171825599880","count":1},{"lng":"121.97925141116000702","lat":"29.81335324424399857","count":1},{"lng":"121.96654822066000179","lat":"29.80203305154499915","count":1},{"lng":"121.96121962927000482","lat":"29.79876428024099866","count":1},{"lng":"121.94649301222000304","lat":"29.79243430893799882","count":1},{"lng":"121.94300499519999903","lat":"29.79132642105500040","count":1},{"lng":"121.93624256578000598","lat":"29.79261412193099900","count":1},{"lng":"121.92976345401000060","lat":"29.79086531288499984","count":1},{"lng":"121.91419359308000026","lat":"29.78270234553000151","count":1}

请问，有什么查询的方法，能够聚合一个点位的数据后，得到查询结果，就是后面的count值是聚合后的值，想到的类似mysql中的group by，但这又不是简单的group by，不知道有什么解决方案