同时对多个字段进行Mongodb聚合(计数)
我有这样的文件:同时对多个字段进行Mongodb聚合(计数),mongodb,mongodb-query,aggregation-framework,Mongodb,Mongodb Query,Aggregation Framework,我有这样的文件: { "_id" : "someuniqueeventid", "event" : "event_type_1", "date" : ISODate("2014-01-14T00:00:00Z"), } db.data.aggregate([ { "$group": { "_id": "$event", "1": { "$sum": { "$cond": [
{
"_id" : "someuniqueeventid",
"event" : "event_type_1",
"date" : ISODate("2014-01-14T00:00:00Z"),
}
db.data.aggregate([
{ "$group": {
"_id": "$event",
"1": {
"$sum": {
"$cond": [
{ "$eq": [{ "$dayOfWeek": "$date" }, 1 ] },
1,
0
]
}
},
"2": {
"$sum": {
"$cond": [
{ "$eq": [{ "$dayOfWeek": "$date" }, 2 ] },
1,
0
]
}
},
"3": {
"$sum": {
"$cond": [
{ "$eq": [{ "$dayOfWeek": "$date" }, 3 ] },
1,
0
]
}
},
"4": {
"$sum": {
"$cond": [
{ "$eq": [{ "$dayOfWeek": "$date" }, 4 ] },
1,
0
]
}
},
"5": {
"$sum": {
"$cond": [
{ "$eq": [{ "$dayOfWeek": "$date" }, 5 ] },
1,
0
]
}
},
"6": {
"$sum": {
"$cond": [
{ "$eq": [{ "$dayOfWeek": "$date" }, 6 ] },
1,
0
]
}
},
"7": {
"$sum": {
"$cond": [
{ "$eq": [{ "$dayOfWeek": "$date" }, 7 ] },
1,
0
]
}
}
}}
)
我想按“事件”
”分组,并计算一周中每天发生的每种事件类型的数量。基本上,我想得到如下结果:
{
"_id": "event_type_1",
"1": "number of event_type_1 for Monday",
"2": "number of event_type_1 for Tuesday",
...
},
{
"_id": "event_type_2",
...
}
不幸的是,我被困在:
db.data.aggregate([ {$project: {date_of_week: {$dayOfWeek: "$date"}, event: "$event"}},
{$group: {_id: "$event", .... } ])
有什么想法吗?聚合框架不会基于数据创建键,您甚至不应该这样做,因为“数据”不是键,而是实际数据,所以您应该坚持这种模式 这意味着您基本上可以这样做:
db.data.aggregate([
{ "$group": {
"_id": {
"event_type": "$event",
"day": { "$dayOfWeek": "$date" }
},
"count": { "$sum": 1 }
}}
])
这将统计每个事件每周每天的发生次数,尽管输出中有多个文档,但这很容易更改为每个事件一个文档:
db.data.aggregate([
{ "$group": {
"_id": {
"event_type": "$event",
"day": { "$dayOfWeek": "$date" }
},
"count": { "$sum": 1 }
}},
{ "$group": {
"_id": "$_id.event_type",
"days": { "$push": { "day": "$_id.day", "count": "$count" } }
}}
])
这是一个数组形式,但它仍然保存您想要的结果
如果你真的致力于做你的精确形式,那么你想做如下事情:
{
"_id" : "someuniqueeventid",
"event" : "event_type_1",
"date" : ISODate("2014-01-14T00:00:00Z"),
}
db.data.aggregate([
{ "$group": {
"_id": "$event",
"1": {
"$sum": {
"$cond": [
{ "$eq": [{ "$dayOfWeek": "$date" }, 1 ] },
1,
0
]
}
},
"2": {
"$sum": {
"$cond": [
{ "$eq": [{ "$dayOfWeek": "$date" }, 2 ] },
1,
0
]
}
},
"3": {
"$sum": {
"$cond": [
{ "$eq": [{ "$dayOfWeek": "$date" }, 3 ] },
1,
0
]
}
},
"4": {
"$sum": {
"$cond": [
{ "$eq": [{ "$dayOfWeek": "$date" }, 4 ] },
1,
0
]
}
},
"5": {
"$sum": {
"$cond": [
{ "$eq": [{ "$dayOfWeek": "$date" }, 5 ] },
1,
0
]
}
},
"6": {
"$sum": {
"$cond": [
{ "$eq": [{ "$dayOfWeek": "$date" }, 6 ] },
1,
0
]
}
},
"7": {
"$sum": {
"$cond": [
{ "$eq": [{ "$dayOfWeek": "$date" }, 7 ] },
1,
0
]
}
}
}}
)
但是这真的很冗长,所以我会坚持使用第一个或第二个解决方案,因为它们更短,更容易阅读。对于MongoDb 3.4.4和更新版本,您可以利用操作符来获取计数。您需要运行以下聚合管道:
db.data.aggregate([
{
"$group": {
"_id": {
"event": "$event",
"day": { "$substr": [ { "$dayOfWeek": "$date" }, 0, -1 ] }
},
"count": { "$sum": 1 }
}
},
{
"$group": {
"_id": "$_id.event",
"counts": {
"$push": {
"k": "$_id.day",
"v": "$count"
}
}
}
},
{
"$project": {
"counts": { "$arrayToObject": "$counts" }
}
}
])
啊!现在似乎很容易,我总是忘记我可以在_id中粘贴多个字段:(谢谢!在第二个示例中,
$day
应该是$_id.day
,没有?$arrayToObject从3.4.4版开始提供。@AsyaKamsky为澄清而欢呼,更新了答案。