Why this chapter matters
Choosing the right structure directly affects correctness, lookup speed, and how easy transformations are to reason about.
What you will learn
- Use lists for ordered sequences and iteration.
- Use dictionaries for key-based lookup and mapping.
- Use sets for uniqueness checks and membership testing.
Lessons in this chapter
- Lists and tuplesPick mutable versus immutable sequence types correctly.
- DictionariesRepresent row-like records and keyed indexes.
- SetsDetect duplicates and run fast membership checks.
- Guide: data structuresBuild a clean record model for analysis tasks. Read the full guide →
Study task
Given two CSV extracts, build a deduplicated list of order IDs and a dictionary keyed by order ID for fast retrieval.
Chapter checkpoint
Which structure is best for repeated membership checks on unique IDs?
A set, because it stores unique values and provides fast membership testing.