mongoose - MongoDB GeoNear Aggregate -

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the question is:

consider following location: [-72, 42] , range (circle) of radius 2 around point. write query find states intersect range (circle). then, should return total population , number of cities each of these states. rank states based on number of cities.

i have written far:

db.zips.find({loc: {$near: [-72, 42], $maxdistance: 2}})

and sample output of is: { "city" : "woodstock", "loc" : [ -72.004027, 41.960218 ], "pop" : 5698, "state" : "ct", "_id" : "06281" }

in sql group "state", how able here while counting cities , total population?

assuming follow mongoimport routine zipcode data (i brought mine collection called zips7):

mongoimport --db mydb --collection zips7 --type json --file c:\users\drew\downloads\zips.json

or

mongoimport --db mydb --collection zips7 --type json --file /data/playdata/zips.json

(depending on os , paths)

then

db.zips7.ensureindex({loc:"2d"})

db.zips7.find({loc: {$near: [-72, 42], $maxdistance: 2}}).foreach(function(doc){    db.zips8.insert(doc); });

note db.zips7.stats() shows 30k rows , zips8 has 100 rows

 db.zips8.aggregate( { $group :  { _id : "$state",    totalpop : { $sum : "$pop" },    town_count:{$sum:1}   }}  )    {         "result" : [                 {                         "_id" : "ri",                         "totalpop" : 39102,                         "town_count" : 10                 },                 {                         "_id" : "ma",                         "totalpop" : 469583,                         "town_count" : 56                 },                 {                         "_id" : "ct",                         "totalpop" : 182617,                         "town_count" : 34                 }         ],         "ok" : 1 }

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