車輛監控項目，記錄車輛GPS定位數據，我們在偵測浙江省高速道路的時候，GPS熱力圖顯示，結果變成這樣了，如圖：

##MongoDB裡，儲存資料的格式是這樣滴

{

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

}

通過查詢後，返回json格式是這樣的：

{"lng":"121.98826732480999624","lat":"29.88628748150999925","count":1},{"lng":"122.00810540175000 "count":1} ,{"lng":"122.00148151521000273","lat":"29.82556419141700133","count":1},{"lng":"122.09566082377000lat38" count":1},{ "lng":"121.99538599286999840","lat":"29.82299558164600128","count":1},{"lng":"121.984819960319958603199586"lng" 1},{"lng ":"121.97925141116000702","lat":"29.81335324424399857","count":1},{"lng":"121.966548220660001795," {"lng": "121.96121962927000482","lat":"29.79876428024099866","count":1},{"lng":"121.94649301222000304"9." lng":"121.94300499519999903 ","lat":"29.79132642105500040","count":1},{"lng":"121.93624256578000598","lat":"29.792614121930999000," 0060", "lat":"29.79086531288499984","count":1},{"lng":"121.91419359308000026","lat":"29.78270234553000151","lat":"29.78270234553000151","lat":}##"

請問，有什麼查詢的方法，能夠聚合一個點位的資料後，得到查詢結果，就是後面的count值是聚合後的值，想到的類似mysql中的group by，但這又不是簡單的group by，不知道有什麼解決方案