Choosing the Right Structure
A practical decision guide: list vs tuple vs set vs dict, with real tasks like membership, ordering, uniqueness, and key-based access.
Most beginners ask: “Which one should I use?” Here is the simple decision system. ## Use list when - order matters - you need duplicates - you need indexing ## Use tuple when - order matters - you want data to be fixed (no changes) ## Use set when - uniqueness matters - you need fast membership tests ## Use dict when - you need key -> value lookup ## Examples ### Task: store user order list Use list: ```python queue = ["Tom", "Sarah", "Mike"] ``` ### Task: store unique user emails Use set: ```python emails = {"a@x.com", "b@x.com"} ``` ### Task: store user profile by id Use dict: ```python users = {101: {"name":"Tom"}, 102: {"name":"Sarah"}} ``` ## Graph: quick decision ```mermaid flowchart TD A[Need a container] --> B{Need key->value?} B -->|Yes| C[dict] B -->|No| D{Need uniqueness?} D -->|Yes| E[set] D -->|No| F{Need fixed/unchangeable?} F -->|Yes| G[tuple] F -->|No| H[list] ``` ## Remember - Choose based on operations, not personal preference - Correct structure makes code simpler and faster