Data Cleaning Exercises

Dataset pack

Device last-seen dates

A device inventory extracted on 30 June 2026, with clock errors and devices that went quiet.

Fictional data · UTF-8 CSV, every value quoted so padding and leading zeros survive; empty fields are missing values · free for personal and classroom practice · practise it in Future dates are errors, old dates are stale.

devices 18 rows × 3 columns

Download devices.csv (Pro)

Data dictionary

id
Unique device ID.
name
Device name.
last_seen
Date the device last checked in, YYYY-MM-DD.

Values are shown in quotes so leading and trailing spaces are visible. ∅ means the cell is missing. Exercises are also graded on hidden datasets that are never published.