MongoDB 聚合 - 如何获取一周中每天发生事件次数的百分比值

Question

我是 MongoDB 菜鸟，所以如果我的问题很愚蠢，请不要评判我：P\n我试图从 MongoDB 获取一些结果来创建一个表，该表将显示我每周每天玩某个游戏的百分比统计数据（所有游戏）每天在一起 = 100%）。这是我的数据库 JSON 导入：

\n\n

[\n{"title":"GTA","date":"2017-11-13"},\n{"title":"GTA","date":"2017-11-13"},\n{"title":"BattleField","date":"2017-11-13"},\n{"title":"BattleField","date":"2017-11-13"},\n{"title":"BattleField","date":"2017-11-14"}\n]\n

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我编写了一个聚合，按天对结果进行分组，并计算每天玩游戏的总次数\xe2\x80\xa6：

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db.games.aggregate([\n    { $project: { _id: 0, date : { $dayOfWeek: "$date" }, "title":1} },\n    { $group: { _id: {title: "$title", date: "$date"}, total: {$sum: 1} } }, \n    { $group: { _id: "$_id.date", types: {$addToSet: {title:"$_id.title", total: "$total"} } } }\n])\n

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\xe2\x80\xa6 这是我现在从 MongoDB 得到的：

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/* 1 */\n{\n    "_id" : 3, \n    "types" : [\n        {\n            "title" : "BattleField",\n            "total" : 1.0\n        }\n    ]\n},\n\n/* 2 */\n{\n    "_id" : 2, \n    "types" : [\n        {\n            "title" : "GTA",\n            "total" : 2.0\n        },\n        {\n            "title" : "BattleField",\n            "total" : 2.0\n        }\n    ]\n}\n

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我需要得到的是一个如下所示的表：

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            Monday      Tuesday\nGTA         50,00%      0%\nBattleField 50,00%      100%\n

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您能告诉我如何从 Mongo 获得这样的百分比结果吗？

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Answer 1

您的尝试非常接近解决方案！以下内容应该为您指明正确的方向：

aggregate([
    { $project: { "_id": 0, "date" : { $dayOfWeek: "$date" }, "title": 1 } }, // get the day of the week from the "date" field
    { $group: { "_id": { "title": "$title", "date": "$date" }, "total": { $sum: 1 } } }, // group by title and date to get the total per title and date
    { $group: { "_id": "$_id.date", "types": { $push: { "title": "$_id.title", total: "$total" } }, "grandTotal": { $sum: "$total" } } }, // group by date only to get the grand total
    { $unwind: "$types" }, // flatten grouped items
    { $project: { "_id": 0, "title": "$types.title", "percentage": { $divide: [ "$types.total", "$grandTotal" ] }, "day": { $arrayElemAt: [ [ "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" ], "$_id" ] } } }, // calculate percentage and beautify output for "day"
])

结果：

{
    "title" : "BattleField",
    "percentage" : 0.5,
    "day" : "Tue"
}
{
    "title" : "GTA",
    "percentage" : 0.5,
    "day" : "Tue"
}
{
    "title" : "BattleField",
    "percentage" : 1.0,
    "day" : "Wed"
}