ArangoDB(六)——Geo(collection)

collection

座標包括經度和緯度，可以將兩者存儲爲一個屬性，也可以分開爲兩個屬性存儲。ArangoDB允許座標查詢。所以今天的主要內容時創建座標和查詢座標。

Create Collection

• 創建數據

  數據來自各城市的座標數據。

  • 創建集合Collection（比如命名爲Locations）
  • 插入數據

    let places = [
        {"name":"Dragostone","coordinate":[55.167801,-6.815096]},
        {"name":"King's Landing","coordinate":[42.639752,18.110189]},
        {"name":"The Red Keep","coordinate":[35.896447,14.446442]},
        {"name":"Winterfell","coordinate":[54.368321,-5.581312]},
        {"name":"Vaes Dothrak","coordinate":[54.16776,-6.096125]},
        {"name":"Beyond the wall","coordinate":[64.265473,-21.094093]},
        {"name":"Yukai","coordinate":[31.046642,-7.129532]},
        {"name":"Astapor","coordinate":[31.50974,-9.774249]}
        ]
    for item in places
    insert item into Locations
    return NEW
    

• 創建座標索引
  創建座標索引的步驟如下：

  • Go to COLLECTIONS
  • Click on the Locations collection
  • Switch to the Indexes tab at top
  • Click the geen button with a plus on the right -hand side
    
  • Change the type to Geo Index
    
  • Enter coordinate into the Fields field
    
  • Click Create to confirm
    

Query Collection

• NEAR()

  • 語法 ：NEAR(collection, latitude, longitude, limit, distanceName)
  • 🌰
    • 帶collection, latitude, longitude， limit參數

      FOR item IN NEAR(Locations, 55.167801, -6.815096,4)  
      RETURN item
      

    • 帶collection, latitude, longitude, limit，distanceName參數

      FOR item IN NEAR(Locations, 55.167801, -6.815096,4,"distName")  
      RETURN item
      

• WITHIN()

  • 語法：WITHIN(coll, latitude, longitude, radius, distanceName)

  • 🌰

    FOR item IN WITHIN(Locations, 55.167801, -6.815096, 120000,"dist")
    RETURN item
    

  注意 ：3.4.0+ 版本中很少使用NEAR()和WITHIN()，而是用DISTANCE()來代替，接下來看下DISTANCE()：

• DISTANCE()

  • 語法：DISTANCE(latitude1, longitude1, latitude2, longitude2)

  • 🌰

    FOR item IN Locations
      SORT DISTANCE(doc.latitude, doc.longitude, 55.167801, -6.815096)
      limit 3
      RETURN item
    

綜合案例——A geo demonstration using Foxx

• Preparations
  • Installation Foxx

    Arangodb Web UI—— Services——add Service——Upload——導入下載的.zip格式文件

  • 創建集合restaurants和neighborhoods
  • 創建索引
    • restaurants：(type: “geo”, fields: [ “location” ], geoJson:true )
    • neighborhoods(type: “geo”, fields: [ “geometry” ], geoJson:true )
  • 導入數據

    分別向2個集合中導入數據(下載文件的data文件中)

• Usage
  

學習資料

• Geo functions
• Foxx