Enrollments in Missing Courses

PandasEasyJunior level~10 min

Problem

You are given two DataFrames. `course` has columns `course_id` and `label`, one row per course offered by the academy (`course_id` is unique). `enrollment` has columns `enroll_id`, `learner`, and `course_id` (`enroll_id` is unique). A `course_id` should reference a real course, but because of a data-entry bug some enrollments point at a `course_id` that does not exist in `course`.

Report every enrollment whose `course_id` does **not** appear in `course`. Return `enroll_id` and `learner`. Rows may be in any order.

**Example**

```text
course:
+-----------+---------+
| course_id | label |
+-----------+---------+
| 1 | Algebra |
| 2 | Optics |
+-----------+---------+

enrollment:
+-----------+---------+-----------+
| enroll_id | learner | course_id |
+-----------+---------+-----------+
| 100 | Priya | 1 |
| 101 | Marcus | 9 |
| 102 | Lena | 2 |
+-----------+---------+-----------+

Result:
+-----------+---------+
| enroll_id | learner |
+-----------+---------+
| 101 | Marcus |
+-----------+---------+
```

Enrollment 101 points at course 9, which has no matching row in course, so it is the only invalid enrollment.

Input data

Example rows — the live problem includes the full dataset.

course

course_id	label
1	Algebra
2	Optics

enrollment

enroll_id	learner	course_id
100	Priya	1
101	Marcus	9
102	Lena	2

Expected output

Your answer should return 1 row with the columns enroll_id, learner.

Starter code (Pandas (Python))

import pandas as pd

def enrollments_in_missing_courses(course, enrollment) -> pd.DataFrame:
    # Your code here
    return enrollment

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