How to calculate mean etc over multiple columns

[Steve]

import os
from quixstreams import Application, State
import uuid
from dotenv import load_dotenv
from datetime import datetime

load_dotenv("./.env")

app = Application.Quix(str(uuid.uuid4()), auto_offset_reset="earliest")
input_topic = app.topic(os.environ["input"], value_deserializer='json')
#output_topic = app.topic(os.environ["output"], value_serializer='json')

sdf = app.dataframe(input_topic)
sdf = sdf[sdf.contains("location-speed")]

sdf = sdf[["Timestamp", "location-speed"]]

def reduce_mean(state: dict, row:dict):
    
    state["sum_speed"] += row["location-speed"]
    state["count_speed"] += 1
    
    return state

def init_mean(row: dict):
    return {
        "sum_speed": row["location-speed"],
        "count_speed": 1
    }

sdf = sdf.tumbling_window(60000).reduce(reduce_mean, init_mean).final()

sdf = sdf.apply(lambda row: {
    "timestamp": row["start"],
    "mean_speed": row["value"]["sum_speed"] / row["value"]["count_speed"]
})

sdf = sdf.update(lambda row: print((row)))
#sdf = sdf.to_topic(output_topic)

if __name__ == "__main__":
    app.run(sdf)

Discussion on internal slack:
https://quixworld.slack.com/archives/C04KXLCGQ94/p1709129051812289

[Daniil Gusev]

Hey @SteveRosam !

Thanks for the example.

Question: why not to use .mean() instead for your case?

Here is how it could look like:

sdf = sdf[sdf.contains("location-speed")]

sdf = sdf[["Timestamp", "location-speed"]]

sdf = sdf.apply(lambda value: value['location-speed']).tumbling_window(60000).mean().final()

sdf = sdf.apply(lambda row: {
    "timestamp": row["start"],
    "mean_speed": row["value"]
})

sdf = sdf.update(lambda row: print((row)))

[Daniil Gusev]

The similar example is available in the library docs - https://quix.io/docs/quix-streams/windowing.html#reduce