python操作mongodb之二彙總查詢

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#彙總查詢from pymongo import MongoClientdb = MongoClient(‘mongodb://10.0.0.9:27017/‘).aggregation_example#準備資料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#$unwind 解開-後面的變數pipeline = [     {"$unwind": "$tags"},     {"$group": {"_id": "$tags", "count": {"$sum": 1}}},     {"$sort": SON([("count", -1), ("_id", -1)])} ]list(db.things.aggregate(pipeline))#使用彙總函式with commanddb.command(‘aggregate‘, ‘things‘, pipeline=pipeline, explain=True)"""Map/Reduce"""from bson.code import Codemapper = 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

　　

python操作mongodb之二彙總查詢