Level 6Exercise #145

Group events by day

Group (ISO timestamp, event) pairs by calendar date.

What you’ll practice

This Level 6 exercise focuses on datetime.date in the Professional curriculum. Solve the challenge prompt above using clear, idiomatic Python and the relevant language or standard-library tools.

Relevant Python reference: datetime — Basic date and time types.

Sample Test Cases

Example #1

Input:events_by_day([('2026-08-05T10:00:00', 'e1'), ('2026-08-05T12:00:00', 'e2')])

Output:{date(2026,8,5): [...]}

Reference Solution

Reveal Reference Solution

def events_by_day(rows: list[tuple[str,str]]):
    from collections import defaultdict
    from datetime import datetime
    grouped = defaultdict(list)
    for timestamp, event in rows:
        grouped[datetime.fromisoformat(timestamp).date()].append(event)
    return dict(grouped)

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Group events by day

What you’ll practice

Sample Test Cases

Further Reading

Reference Solution