[{"gender":"male","name":"James","location":"Brazil","email":"james@sample.com"},{"gender":"female","name":"Jonna","location":"Canada","email":"jonna@sample.com"},{"gender":"male","name":"Rom","location":"Canada","email":"rom@sample.com"},{"gender":"female","name":"Lily","location":"India","email":"lily@sample.com"}]

db.collection.aggregate([{"$group":{"_id":"$location","users":{"$push":{"name":"$name","email":"$email","gender":"$gender"}}}},{"$project":{"_id":0,"name":"$_id","users":1}},{"$sort":{"name":1}}])