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- $centerSphere
$centerSphere¶
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Definition¶
- $centerSphere¶
New in version 1.8.
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 Calculate Distance Using Spherical Geometry.
{ <location field>: { $geoWithin: { $centerSphere: [ [ <x>, <y> ], <radius> ] } } }
Important
If you use longitude and latitude, specify longitude first.
Behavior¶
Changed in version 2.2.3: Applications can use $centerSphere without having a geospatial index. However, geospatial indexes support much faster queries than the unindexed equivalents. Before 2.2.3, a geospatial index must exist on a field holding coordinates before using any of the geospatial query operators.
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 ] } }
} )
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