Convert Sql query into mongodb type with pymongo

Hi guys.I am trying to convert an sql query into mongodb type.
The sql query look like this:

"select date_trunc('day',timestamp1) as day,avg(id9) from oneindextwocolumns where timestamp1>='2010-01-01 00:00:00' and timestamp1<='2020-12-31 00:55:00'  group by day,id13 order by day asc "

This is what i have tried for mongodb:

cursor=mydb1.mongodbtime.aggregate([

    {
        "$match": {
            "timestamp1": {"$gte": datetime.strptime("2010-01-01 00:00:00", "%Y-%m-%d %H:%M:%S"),
                          "$lte" :datetime.strptime("2020-12-31 00:55:00", "%Y-%m-%d %H:%M:%S")}
        }
    },

{
        "$group": {
            "_id":{
                "date": {"$dateToString": { "format": "%Y-%m-%d ", "date": "$timestamp1" }},
                 "id13":"$id13",

        },
            "avg_id9": {
                "$avg": "$id9"
            }
      }
},
    {
        "$project": {
            "_id": 0,
            "day":"$_id.date",
            "avg_id9":1

        }
    },
    {"$sort": {"day": 1}}

])

But i dont get the same results in mongodb.What am i doing wrong?Does this have any thing to do with indexing?i have one compound index in psql table timestamp1 desc,id13 asc?I dont have index in mongodb table yet!
Edit:It seems tha the results where the same but not in the right order!

Thanks in advance!