Riders per Ferry I

Problem

A harbour logs ferry departures in a DataFrame `ferries` with columns `(ferry_id, depart_time)` and rider arrivals in a DataFrame `riders` with columns `(rider_id, arrive_time)` (both loaded from CSVs). Times are integers; `ferry_id` and `rider_id` are unique.

Each rider boards the next ferry whose `depart_time` is greater than or equal to that rider's `arrive_time`. Return `ferry_id` and `rider_count` (how many riders board it) for every ferry, including ferries nobody boards, ordered by `ferry_id` ascending.

Input data

Example rows — the live problem includes the full dataset.

Expected output

Your answer should return 3 rows with the columns ferry_id, rider_count.

Starter code (Pandas (Python))

import pandas as pd

def riders_per_ferry_i(ferries, riders) -> pd.DataFrame:
    # Your code here
    return ferries

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