Tight Collaborations

PandasMediumMid level~10 min

Problem

A research platform records which scholars have co-authored together.

You are given one DataFrame `coauthors`:

| Column | Type |
|------------|------|
| author1_id | int |
| author2_id | int |

`(author1_id, author2_id)` is unique. Each row means the two authors have co-authored. Co-authorship is mutual, but each pair is stored once with `author1_id < author2_id`.

A co-authorship between authors x and y is **tight** if x and y have at least three **common co-authors** (a third author who has co-authored with both x and y).

Return a DataFrame with `author1_id`, `author2_id`, and `common_count` for every tight co-authorship (`author1_id < author2_id`), in any order.

Input data

Example rows — the live problem includes the full dataset.

coauthors

author1_id	author2_id
1	2
1	3
2	3
1	4
2	4

Expected output

Your answer should return 3 rows with the columns author1_id, author2_id, common_count.

Starter code (Pandas (Python))

import pandas as pd

def tight_collaborations(coauthors: pd.DataFrame) -> pd.DataFrame:
    # Your code here
    return coauthors

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