The Pandas Pivot

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

Domain

Python

Difficulty

medium

Seniority

L4

Problem

Given a list of event dicts (each with 'user_id', 'event_type', 'amount'), pivot so each user becomes one dict containing one column per distinct event_type (whose value is the sum of that user's amounts for that event_type) plus a final 'user_id' column. Only include event_type columns the user actually has (a sparse pivot; missing event_types are simply absent). Within each user's dict, place the event_type columns first, ordered by descending summed amount, and put 'user_id' last. Return the list of per-user dicts sorted by user_id ascending.

Summary

Rows become columns. Columns become power.

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