The Map Reducer

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

Domain

Python

Difficulty

medium

Seniority

L3

Problem

Given a list of values, a mapper (single-arg function or lambda source string), and a reducer (two-arg function or lambda source string), apply mapper to each value, then reduce left-to-right with reducer. Return the final reduced value, or None if values is empty. If mapper or reducer is a string, eval it into a callable first.

Summary

Map it. Reduce it. One answer.

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