hw2-2.js

hw2-2.js

/*global db,print*/
var m = db.grades.aggregate(
    {'$match': {'type': 'homework'}},
    {'$project': {"student_id": 1, "_id": 1, "score": 1}},
    {"$group": {"_id": "$student_id", "min": {"$min": "$score"}}}
).result;

for (var i in m) {
    db.grades.remove({ 'student_id': m[i]._id, 'score': m[i].min });
}

print(db.grades.aggregate(
    {'$group':{'_id':'$student_id', 'average':{$avg:'$score'}}},
    {'$sort':{'average':-1}}, {'$limit':1}).result[0]._id);