frozenset({1,2,3}).intersection

Built-in Data Structures

Meaning

Creates an immutable frozenset from an iterable and computes its intersection with another iterable, returning a new frozenset containing only the elements present in both.

Primary Function

Set operations

Communicative Purpose

Find common elements while guaranteeing the result is hashable for use as a dictionary key or set element.

Pattern

frozenset(first_set).intersection(second_set)

Core Structure

frozenset(...).intersection(...)

Função primária

Set operations

Propósito comunicativo

Find common elements while guaranteeing the result is hashable for use as a dictionary key or set element.

Situações de gatilho

Data processing: need an immutable set for hashing keys Algorithm design: require set intersection while preserving hashability

Contextos

Data processing pipelines, graph algorithms, caching mechanisms, and any code that benefits from hashable intermediate results.

Padrão

frozenset(first_set).intersection(second_set)

Estrutura central

frozenset(...).intersection(...)

Slots de substituição

first_set: iterable of hashable items (e.g., list, set, tuple); second_set: iterable of hashable items

Colocados típicos

set
list
tuple
& operator
frozenset.union

Substituições comuns

frozenset(first_set) & second_set
set(first_set).intersection(second_set) (returns mutable set)

Erros comuns

Using a mutable set when immutability is required; forgetting that intersection returns a new frozenset rather than modifying in place; expecting the result to be a list or tuple.

Similar / contraste

set.intersection (returns a mutable set); frozenset.union; using the & operator on two frozensets.

Interferências

Coming from languages where set intersection is a function that modifies arguments (e.g., MATLAB's intersect), one might expect in-place behavior.

Família do chunk

frozenset creation
set operations
immutable collections

Nuance

The result is always a frozenset; if a mutable set is needed, wrap the result with set(). The method accepts any iterable, not just sets.

Efeito pragmático

Guarantees hashability, allowing the intersection result to be safely used as a dictionary key or element of another set without risk of accidental mutation.

Dica de memória

Think ‘freeze then meet’ – freeze the first set, then find the common elements.

Nota

Use frozenset.intersection to obtain an immutable, hashable intersection suitable for dictionary keys or set elements.

Upgrade path

Use the concise & operator: frozenset(first_set) & second_set, or intersect multiple sets with frozenset(first_set).intersection(*sets).

Frequência: MediumFormulaicidade: Semi-fixedTipo de construção: method_chainPrioridade de aquisição: Recognition firstPrioridade de output: BothTag de espaçamento: Medium-term

Examples

fs = frozenset({1, 2, 3}) result = fs.intersection({2, 3, 4}) print(result) # frozenset({2, 3})

fs = frozenset([1, 2, 3, 4]) other = (3, 4, 5, 6) common = fs.intersection(other) print(common) # frozenset({3, 4})

# Use frozenset intersection as a dict key data = { frozenset({'a', 'b'}).intersection({'b', 'c'}): 'value' } print(data) # {frozenset({'b'}): 'value'}