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Query a 2dsphere Index

The following sections describe queries supported by the 2dsphere index.

GeoJSON Objects Bounded by a Polygon

The $geoWithin operator queries for location data found within a GeoJSON polygon. Your location data must be stored in GeoJSON format. Use the following syntax:

copy

db.<collection>.find( { <location field> :
                         { $geoWithin :
                           { $geometry :
                             { type : "Polygon" ,
                               coordinates : [ <coordinates> ]
                      } } } } )

The following example selects all points and shapes that exist entirely within a GeoJSON polygon:

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db.places.find( { loc :
                  { $geoWithin :
                    { $geometry :
                      { type : "Polygon" ,
                        coordinates : [ [
                                          [ 0 , 0 ] ,
                                          [ 3 , 6 ] ,
                                          [ 6 , 1 ] ,
                                          [ 0 , 0 ]
                                        ] ]
                } } } } )

Intersections of GeoJSON Objects

The $geoIntersects operator queries for locations that intersect a specified GeoJSON object. A location intersects the object if the intersection is non-empty. This includes documents that have a shared edge.

The $geoIntersects operator uses the following syntax:

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db.<collection>.find( { <location field> :
                         { $geoIntersects :
                           { $geometry :
                             { type : "<GeoJSON object type>" ,
                               coordinates : [ <coordinates> ]
                      } } } } )

The following example uses $geoIntersects to select all indexed points and shapes that intersect with the polygon defined by the coordinates array.

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db.places.find( { loc :
                  { $geoIntersects :
                    { $geometry :
                      { type : "Polygon" ,
                        coordinates: [ [
                                         [ 0 , 0 ] ,
                                         [ 3 , 6 ] ,
                                         [ 6 , 1 ] ,
                                         [ 0 , 0 ]
                                       ] ]
                } } } } )

Proximity to a GeoJSON Point

Proximity queries return the points closest to the defined point and sorts the results by distance. A proximity query on GeoJSON data requires a 2dsphere index.

To query for proximity to a GeoJSON point, use either the $near operator. Distance is in meters.

The $near uses the following syntax:

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db.<collection>.find( { <location field> :
                         { $near :
                           { $geometry :
                              { type : "Point" ,
                                coordinates : [ <longitude> , <latitude> ] } ,
                             $maxDistance : <distance in meters>
                      } } } )

For examples, see $near.

See also the $nearSphere operator and the:pipeline:$geoNear aggregation pipeline stage.

Points within a Circle Defined on a Sphere

To select all grid coordinates in a “spherical cap” on a sphere, use $geoWithin with the $centerSphere operator. Specify an array that contains:

• The grid coordinates of the circle’s center point
• The circle’s radius measured in radians. To calculate radians, see Calculate Distance Using Spherical Geometry.

Use the following syntax:

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db.<collection>.find( { <location field> :
                         { $geoWithin :
                           { $centerSphere :
                              [ [ <x>, <y> ] , <radius> ] }
                      } } )

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

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

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