Voli: 10 top Aeroporti con il maggior numero di compagnie ae

db.parsed_data.aggregate(

{$match : {$and: [
    {$and: [{"Segments.From.Country":{$ne: null} }, {"Segments.To.Country" :{$ne: null} },{"Segments" :{"$size":1}}]},
    {"SearchDate": { $gte: ISODate("2017-03-17T00:00:00.000+01:00"), $lte: ISODate("2017-04-17T00:00:00.000+01:00") }}]}}
    ,


        {
            $group :   {_id : "$Segments.To.Code" ,
                        "company" :{$addToSet: {"carrier": "$Segments.Carrier"}},
                        "total" : { $sum : 1 }}

        },
 {$sort : {total : -1}})