The Stream Averager

A easy Python interview practice problem on DataDriven. Write and execute real python code with instant grading.

Domain

Python

Difficulty

easy

Seniority

L5

Problem

Implement the StreamAverager class with add(key, value) and get_averages(). add(key, value) records one numeric reading for key. get_averages() returns a dict mapping each key seen so far to the average (mean) of its values; before any reading is added it returns an empty dict {}. A driver run_stream_averager(operations) is provided: operations is a list where each entry is either ['add', key, value] or ['get_averages']. Create a single StreamAverager, apply the operations in order on it, and return a parallel list of results: None for each 'add' and the dict for each 'get_averages'. Averages are floats (e.g. add('sensor_a', 10), add('sensor_a', 30), get_averages() -> {'sensor_a': 20.0}).

Summary

The answer moves with the data.

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