1 2
3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 |
#聚合查询 from pymongo import MongoClient db = MongoClient( 'mongodb://10.0.0.9:27017/' ).aggregation_example #准备数据 result = db.things.insert_many([{ "x" : 1 , "tags" : [ "dog" , "cat" ]}, { "x" : 2 , "tags" : [ "cat" ]}, { "x" : 2 , "tags" : [ "mouse" , "cat" , "dog" ]}, { "x" : 3 , "tags" : []}]) result.inserted_ids ''' { "_id" : ObjectId("576aaa973e5269020848cc7c"), "x" : 1, "tags" : [ "dog", "cat" ] } { "_id" : ObjectId("576aaa973e5269020848cc7d"), "x" : 2, "tags" : [ "cat" ] } { "_id" : ObjectId("576aaa973e5269020848cc7e"), "x" : 2, "tags" : [ "mouse", "cat", "dog" ] } { "_id" : ObjectId("576aaa973e5269020848cc7f"), "x" : 3, "tags" : [ ] } ''' from bson.son import SON #$unwind 解开-后面的变量 pipeline = [ { "$unwind" : "$tags" }, { "$group" : { "_id" : "$tags" , "count" : { "$sum" : 1 }}}, { "$sort" : SON([( "count" , - 1 ), ( "_id" , - 1 )])} ] list (db.things.aggregate(pipeline)) #使用聚合函数with command db.command( 'aggregate' , 'things' , pipeline = pipeline, explain = True ) """Map/Reduce""" from bson.code import Code mapper = Code( """ function () { this.tags.forEach(function(z) { emit(z, 1); }); } """ ) reducer = Code( """ function (key, values) { var total = 0; for (var i = 0; i < values.length; i++) { total += values[i]; } return total; } """ ) result = db.things.map_reduce(mapper, reducer, "myresults" ) for doc in result.find(): print doc |