Method for querying whether a certain coordinate is within a specified polygonal area using MongoDB

Introduction

As everyone knows, MongoDB is a database based on distributed file storage and provides the ability to create geospatial indexes. This article will use MongoDB's geospatial index to judge the area of coordinates and use it.

1Use the Baidu Coordinate Acquisition Tool to define the coordinates of the polygon on the map and save the coordinates of each point.

Baidu Coordinate Acquisition Tool：http://api.map.baidu.com/lbsapi/getpoint/

The coordinates of the polygon are as follows：

113.314882,23.163055
113.355845,23.167042
113.370289,23.149564
113.356779,23.129758
113.338238,23.13913
113.330979,23.124706
113.313588,23.140858
113.323865,23.158204
113.314882,23.163055

Note：The start and end coordinates must be the same to ensure that the polygon is closed.

2Use the Baidu Map Open Platform Map JS Demo to input the coordinates of the polygon and see if the polygon is suitable.

Baidu Map Open Platform Map JS Demo：http://developer.baidu.com/map/jsdemo.htm#c2_9

Replace the following code in the source code editor and then click to run

<!DOCTYPE html>
<html>
<head>
 <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
 <meta name="viewport" content="initial-scale=1.0, user-scalable=no" />
 <style type="text/css">
 body, html{width: 100%;height: 100%;margin:0;font-family:"Microsoft YaHei";}
 #allmap {height:100%; width: 100%;}
 #control{width:100%;}
 </style>
 <script type="text/javascript" src="http://api.map.baidu.com/api?v=2.0&ak=Your key"></script>
 <title>Set line and area editable</title>
</head>
<body>
 <div id="allmap"></div>
 <div id="control">
 <button onclick = "polyline.enableEditing();polygon.enableEditing();">Open line and area editing features</button>
 <button onclick = "polyline.disableEditing();polygon.disableEditing();">Close line and area editing features</button>
 </div>
</body>
</html>
<script type="text/javascript">
 // Baidu Map API features
 var map = new BMap.Map("allmap");
 map.centerAndZoom(new BMap.Point(113.330764,23.155878), 15);
 map.enableScrollWheelZoom();
 var polygon = new BMap.Polygon([
 new BMap.Point(113.314882,23.163055),
 new BMap.Point(113.355845,23.167042),
 new BMap.Point(113.370289,23.149564),
 new BMap.Point(113.356779,23.129758),
 new BMap.Point(113.338238,23.13913),
 new BMap.Point(113.330979,23.124706),
 new BMap.Point(113.313588,23.140858),
 new BMap.Point(113.323865,23.158204)
 ], {strokeColor:"blue", strokeWeight:2, strokeOpacity:0.5}); //Create polygon
 map.addOverlay(polygon); //Add polygon
</script>

Polygon area

3.Define test coordinates

Guangzhou East Station coordinates:113.330908,23.155678 (Inside polygon)

Mafang Building:113.33831,23.137335 (Outside polygon)

4.In MongoDB test

1.Create database

use testdb;
db.createUser( 
 { 
 "user":"root", 
 "pwd":"123456", 
 "roles":[{"role" : "readWrite", "db":"testdb"}] 
 } 
);
db.auth( 
 { 
 "user":"root", 
 "pwd":"123456" 
 } 
);

2.Insert polygonal range and add index

db.geo.ensureIndex( 
 { 
 polygons: "2dsphere" 
 } 
);
db.geo.insert(
 {
 polygons:
 {
 type:"Polygon",
 coordinates:[[
 [113.314882,23.163055,
 [113.355845,23.167042,
 [113.370289,23.149564,
 [113.356779,23.129758,
 [113.338238,23.13913,
 [113.330979,23.124706,
 [113.313588,23.140858,
 [113.323865,23.158204,
 [113.314882,23.163055,
 ]]
 }
 }
);

3.Judge whether the coordinates are in the polygonal area

Guangzhou East Station coordinates:113.330908,23.155678

db.geo.find(
 {
 polygons:
 {
 $geoIntersects:
 {
 $geometry:{ 
  "type" : "Point",
  "coordinates" : [113.330908,23.155678}]
 }
 }
 }
);

Output:

{ "_id" : ObjectId("57c2b1895fb7fd4790f9f099"), "polygons" : { "type" : "Polygon", "coordinates" : [ [ [ 113.314882, 23.163055 ], [ 113.355845, 23.167042 ], [ 113.370289, 23.149564 ], [ 113.356779, 23.129758 ], [ 113.338238, 23.13913 ], [ 113.330979, 23.124706 ], [ 113.313588, 23.140858 ], [ 113.323865, 23.158204 ], [ 113.314882, 23.163055 ]] } }

represents the coordinates 113.330908,23.155678 Within the polygonal area

Mafang Building:113.33831,23.137335

db.geo.find(
 {
 polygons:
 {
 $geoIntersects:
 {
 $geometry:{ 
  "type" : "Point",
  "coordinates" : [113.33831,23.137335}]
 }
 }
 }
);

Output:empty

represents the coordinates 113.33831,23.137335 Outside the polygonal area

Summary

That's all about using mongodb to judge whether the coordinates are within the specified polygonal area. I hope the content of this article can bring you some help in learning or work. If you have any questions, you can leave a message for communication, thank you for your support of the Yell tutorial.

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