CODEWITHSUNDEEP
mongodbmongodb-queryaggregation-framework
micoco
micoco

Reputation: 299

Get highest value given a key

I have performed the following query:

db.Indiv2.aggregate(
    {$unwind: '$conso'},
    {$group: {_id: {conso:'$conso.nom_commercial', region:"$region"}, sum: {$sum: 1}}},
    {$sort : {sum : -1}}
);

which returns the following:

    {
        "_id" : {
            "conso" : "x",
            "region" : 1
        },
        "sum" : 73226.0
    },
    {
        "_id" : {
            "conso" : "x",
            "region" : 8
        },
        "sum" : 25683.0
    },
    {
        "_id" : {
            "conso" : "grandlait demi �cr�m� uht",
            "region" : 1
        },
        "sum" : 251.0
    }

There are 21 different regions and I am trying to get the most consumed item by region. How could I use "sum" to return the highest value given each region?

Upvotes: 0

Views: 23

Answers (1)

dnickless
dnickless

Reputation: 10918

It should be enough for you to add the following two stages to the end of your aggregation pipeline:

$group: {
    _id: "$_id.region",
    "conso": {
        $first: "$_id.conso"
    },
    "sum": {
        $first: "$sum"
    }
}

Upvotes: 1

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