[{"location":{"type":"Point","coordinates":[12.481633,41.897331]}},{"location":{"type":"Point","coordinates":[12.482343,41.896781]}},{"location":{"type":"Point","coordinates":[12.492342,41.874894]}}]

db.collection.aggregate([{$group:{_id:0,lon:{$push:{$arrayElemAt:["$location.coordinates",0]}},lat:{$push:{$arrayElemAt:["$location.coordinates",1]}},}},{$project:{_id:0,centroid:[{$avg:"$lon"},{$avg:"$lat"}]}}])