Middle-Tier Workshop Topics

PandasMediumMid level~10 min

Problem

Two DataFrames describe sign-ups for workshop topics.

`attendee` (`attendee.csv`) has columns `person_id`, `fullname`, `topic` — one row per person, recording which workshop `topic` they signed up for.

`topic` (`topic.csv`) has columns `topic_id`, `topic` — the catalogue of topics.

Find the workshop topics that are **neither the least popular nor the most popular**: every topic whose sign-up count is **strictly greater than the smallest** topic's count **and strictly less than the largest** topic's count. Return a DataFrame with the single column `topic`. Rows may be in any order.

**Example**

If `Welding` has 3 sign-ups (most), `Origami` has 1 (fewest), and `Pottery` has 2 (strictly between), only `Pottery` is returned.

Input data

Example rows — the live problem includes the full dataset.

attendee

person_id	fullname	topic
1	Ada	Welding
2	Bo	Welding
3	Cy	Welding
4	Di	Pottery
5	Ed	Pottery

topic

topic_id	topic
1	Welding
2	Pottery
3	Origami

Expected output

Your answer should return 1 row with the columns topic.

Starter code (Pandas (Python))

import pandas as pd

def middle_tier_topics(attendee: pd.DataFrame, topic: pd.DataFrame) -> pd.DataFrame:
    # Your code here
    return attendee

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