$centerSphere¶

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Definition
Behavior
Example

Definition¶

$centerSphere¶

1.8 新版功能.

Defines a circle for a geospatial query that uses spherical geometry. The query returns documents that are within the bounds of the circle. You can use the $centerSphere operator on both GeoJSON objects and legacy coordinate pairs.

To use $centerSphere, specify an array that contains:

The grid coordinates of the circle’s center point, and
The circle’s radius measured in radians. To calculate radians, see 使用球面几何计算距离.

{
   <location field>: {
      $geoWithin: { $centerSphere: [ [ <x>, <y> ], <radius> ] }
   }
}

重要

If you use longitude and latitude, specify longitude first.

Behavior¶

Applications can use $centerSphere without having a geospatial index. However, geospatial indexes support much faster queries than the unindexed equivalents.

Both 2dsphere and 2d geospatial indexes support $centerSphere.

Example¶

The following example queries grid coordinates and returns all documents within a 10 mile radius of longitude 88 W and latitude 30 N. The query converts the distance to radians by dividing by the approximate equatorial radius of the earth, 3963.2 miles:

db.places.find( {
  loc: { $geoWithin: { $centerSphere: [ [ -88, 30 ], 10/3963.2 ] } }
} )

← $center $box →