ArangoDB(六)——Geo(collection)

collection

座标包括经度和纬度，可以将两者存储为一个属性，也可以分开为两个属性存储。ArangoDB允许座标查询。所以今天的主要内容时创建座标和查询座标。

Create Collection

• 创建数据

  数据来自各城市的座标数据。

  • 创建集合Collection（比如命名为Locations）
  • 插入数据

    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
    

• 创建座标索引
  创建座标索引的步骤如下：

  • 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()

  • 语法 ：NEAR(collection, latitude, longitude, limit, distanceName)
  • 🌰
    • 带collection, latitude, longitude， limit参数

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

    • 带collection, latitude, longitude, limit，distanceName参数

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

• WITHIN()

  • 语法：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()来代替，接下来看下DISTANCE()：

• DISTANCE()

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

  • 🌰

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

综合案例——A geo demonstration using Foxx

• Preparations
  • Installation Foxx

    Arangodb Web UI—— Services——add Service——Upload——导入下载的.zip格式文件

  • 创建集合restaurants和neighborhoods
  • 创建索引
    • restaurants：(type: “geo”, fields: [ “location” ], geoJson:true )
    • neighborhoods(type: “geo”, fields: [ “geometry” ], geoJson:true )
  • 导入数据

    分别向2个集合中导入数据(下载文件的data文件中)

• Usage
  

学习资料

• Geo functions
• Foxx