使用Mongo聚合框架的共现计数 [英] Co-ocurrence count using Mongo aggregation framework

问题描述

我拥有与客户互动的产品（无重复产品）的文档：

I have this documents with the products that the client interacted with (no repeated products):

{ "client_interactions": [{"productType": "A", "productId": "1"}, {"productType": "A", "productId": "2"}, {"productType": "B", "productId": "9"}]}
{ "client_interactions": [{"productType": "A", "productId": "1"}, {"productType": "A", "productId": "2"}]}
{ "client_interactions": [{"productType": "A", "productId": "1"}, {"productType": "A", "productId": "3"}, {"productType": "C", "productId": "10"}]}

我想如果客户已将产品 1与产品 2同时使用，则计算 A类型的每种产品的同时发生次数。

I want to calculate the count of co-ocurrences for each product of type "A", in the sense that product "1" co-ocurred with product "2" if a client has interacted with both of them.

类似的东西：

{ "co-ocurrences-count" : { "1" : [{ "2": 2}, { "3" : 1}]}, { "2" : [{ "1": 2}]}, { "3" : [{ "1": 1}]}}

我有一个使用map-reduce javascript fu的解决方案功能，但我真的希望它使用MongoDB聚合框架来实现吗？

I have a solution using map-reduce javascript functions, but I really want it to do using the MongoDB aggregation framework, is it possible?

预先感谢。

推荐答案

聚合时间很长，但是有效。这个想法是，您需要基于 client_interactions 数组构建对（x，y）。可以使用 $ reduce 和 $ map 。然后，您需要运行 $ unwind 和几个 $ group 阶段来汇总您的汇总数据。您还需要 $ arrayToObject 才能动态构建密钥。

The Aggregation is pretty long but it works. The idea is that you need to build pairs (x,y) based on your client_interactions array. It can be done using $reduce and $map. Then you need to run $unwind and a couple of $group stages to "wind" your aggregated data. You also need $arrayToObject to build your keys dynamically.

db.collection.aggregate([
    {
        $addFields: {
            "client_interactions": {
                $filter: { input: "$client_interactions", cond: { $eq: [ "$$this.productType", "A" ] } }
            }
        }
    },
    {
        $project: {
            a: {
                $reduce: {
                    input: "$client_interactions",
                    initialValue: [],
                    in: {
                        $concatArrays: [
                            "$$value",
                            { $map: { input: "$client_interactions", as: "c",  in: { x: "$$this.productId", y: "$$c.productId" } } }
                        ]
                    }
                }
            }
        }
    },
    {
        $unwind: "$a"
    },
    {
        $match: {
            $expr: {
                $ne: [ "$a.x", "$a.y" ]
            }
        }
    },
    {
        $sort: {
            "a.x": 1,
            "a.y": 1
        }
    },
    {
        $group: {
            _id: "$a",
            count: { $sum: 1 }
        }
    },
    {
        $group: {
            _id: "$_id.x",
            arr: { $push: { k: "$_id.y", v: "$count" } }
        }
    },
    {
        $group: {
            _id: null,
            "co-ocurrences-count": { $push: { k: "$_id", v: { $arrayToObject: "$arr" } } }
        }
    },
    {
        $project: {
            _id: 0,
            "co-ocurrences-count": { $arrayToObject: "$co-ocurrences-count" }
        }
    }
])

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