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List

Type System & Annotations

Meaning

Represents a list where each element is a tuple containing a string and an integer. Used when you need a collection of key‑value‑like pairs where the key is a string and the value is an integer, e.g., labeling items with counts.

Primary Function

Type annotation

Communicative Purpose

Specifies the expected structure of a collection of string‑int pairs for static type checking.

Pattern

List[Tuple[str, int]]

Core Structure

List[Tuple[str, int]]

Função primária

Type annotation

Propósito comunicativo

Specifies the expected structure of a collection of string‑int pairs for static type checking.

Situações de gatilho

Defining function parameters or return types that hold labeled counts; storing results like word frequencies; processing configuration entries.

Contextos

Python codebases using the typing module, data‑processing scripts, APIs returning aggregated statistics.

Padrão

List[Tuple[str, int]]

Estrutura central

List[Tuple[str, int]]

Slots de substituição

first_type: type (e.g., str), second_type: type (e.g., int)

Colocados típicos

typing.List
typing.Tuple
function signatures
return annotations

Substituições comuns

List[Tuple[int
str]] (swapped)
List[Dict[str
int]]
List[Tuple[str
float]]

Erros comuns

Forgetting to import Tuple and List from typing (Python <3.9); using list literal syntax incorrectly; confusing with List[List[int]].

Similar / contraste

List[Tuple[str, str]] (string‑string pairs), Dict[str, int] (mapping), List[int] (simple list).

Interferências

Coming from languages with built‑in associative arrays (e.g., JavaScript objects): may expect a dict instead of a list of tuples.

Família do chunk

List[Tuple[str
str]]
List[Tuple[int
int]]
List[Tuple[str
float]]

Nuance

In Python 3.9+ you can use builtin list and tuple: list[tuple[str, int]]; the pattern is equivalent but requires from __future__ import annotations for older versions.

Efeito pragmático

Makes intent explicit, enables static type checkers to catch mismatched types.

Dica de memória

Think of a grocery list: each item is a name (string) and its quantity (int).

Nota

Can be used with sorting functions to sort by count then label, e.g., sorted(pairs, key=lambda x: (-x[1], x[0]))

Upgrade path

Use list[tuple[str, int]] (Python 3.9+) or consider TypedDict/NamedTuple for more structured data.

Frequência: MediumFormulaicidade: Fully fixedTipo de construção: parameterized generic typePrioridade de aquisição: Recognition firstPrioridade de output: BothTag de espaçamento: Medium-term

Examples

from typing import List, Tuple def word_counts(words: List[str]) -> List[Tuple[str, int]]: from collections import Counter return sorted(Counter(words).items(), key=lambda x: x[1], reverse=True)

import csv from typing import List, Tuple def load_scores(path: str) -> List[Tuple[str, int]]: scores: List[Tuple[str, int]] = [] with open(path, newline='') as f: reader = csv.reader(f) for row in reader: name, score_str = row scores.append((name, int(score_str))) return scores

from typing import List, Tuple def inventory_report(inventory: dict[str, int]) -> List[Tuple[str, int]]: return [(item, qty) for item, qty in inventory.items() if qty > 0]