Meaning
Creates an immutable frozenset from a range of integers. It solves the problem of needing a hashable collection that cannot be modified, preventing accidental changes. Use it when you need a constant set of numbers as a dictionary key or in set operations.
Primary Function
Data structure creation
Communicative Purpose
Ensures an immutable set of consecutive integers for use where a hashable set is required.
Pattern
frozenset(range(stop))
Core Structure
frozenset(range(...))
Função primária
Data structure creation
Propósito comunicativo
Ensures an immutable set of consecutive integers for use where a hashable set is required.
Situações de gatilho
Configuration: need a constant set of integer keys for a dictionary; Caching: store a fixed set of IDs for fast membership checks; Algorithm design: require a hashable set of consecutive numbers for memoization.
Contextos
General Python code, especially in configuration, constants, or algorithmic code requiring hashable sets.
Padrão
frozenset(range(stop))
Estrutura central
frozenset(range(...))
Slots de substituição
stop: int (non‑negative)
Colocados típicos
- used as dict keys
- in set operations
- with membership tests (in)
Substituições comuns
- set(range(stop)) for a mutable set
- frozenset(iterable) for arbitrary iterables
Erros comuns
Attempting to modify the frozenset (e.g., .add) leading to AttributeError; forgetting that frozenset is hashable and trying to use a mutable set as a dict key; Using frozenset as a sequence (e.g., indexing or slicing) leading to TypeError: 'frozenset' object is not subscriptable.
Similar / contraste
tuple(range(stop)) – immutable sequence; frozenset({0,1,2}) – explicit frozenset literal; set(range(stop)) – mutable set
Interferências
Coming from languages with built-in immutable set types (e.g., C#'s ImmutableHashSet): may expect similar performance characteristics → in Python frozenset materializes the whole range.
Família do chunk
- frozenset
- set
- tuple
- range
- frozenset.from_iterable
Nuance
Do not use when only iteration is needed and memory is a concern, as frozenset materializes the entire range; performance-wise, frozenset(range(n)) uses O(n) time and memory versus O(1) for range; boundary condition: frozenset(range(0)) yields an empty frozenset, which is still hashable.
Efeito pragmático
Guarantees the set cannot be changed after creation, making it safe to share across functions or use as a dictionary key.
Dica de memória
Freeze the range to lock it in.
Nota
Useful for creating hashable constant sets of consecutive integers; note that frozenset(range(n)) materializes the entire range in memory.
Upgrade path
frozenset({x for x in iterable if condition}) – building a frozenset from a comprehension with filtering.
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