Meaning
Creates a deque from a list and inserts an element at the left end.
Primary Function
Creates a double-ended queue and inserts an element at the left side.
Communicative Purpose
Signals the intention to use a deque for efficient front insertions.
Pattern
from collections import deque; d = deque\[[^\]]*\]; d\.appendleft\([^)]*\)
Core Structure
from collections import deque; d = deque([items]); d.appendleft(item)
Função primária
Creates a double-ended queue and inserts an element at the left side.
Propósito comunicativo
Signals the intention to use a deque for efficient front insertions.
Situações de gatilho
When you need to add elements to the front of a sequence efficiently, e.g., implementing a stack or queue.
Contextos
algorithm implementations queue/stack implementations data processing pipelines
Padrão
from collections import deque; d = deque\[[^\]]*\]; d\.appendleft\([^)]*\)
Estrutura central
from collections import deque; d = deque([items]); d.appendleft(item)
Slots de substituição
items: iterable, item: any object
Colocados típicos
- collections deque appendleft pop popleft extend extendleft
Substituições comuns
- append extend extendleft pop popleft
Erros comuns
forgetting to import deque using append instead of appendleft using list.insert(0, item) which is O(n)
Similar / contraste
append (right append) extendleft (adds iterable to left) list.insert(0, item)
Interferências
Confusing appendleft with append (adds to right) Confusing deque with list leading to O(n) insertions
Família do chunk
- deque_operations
Nuance
appendleft provides O(1) insertion at the left end, unlike list.insert(0, item) which is O(n).
Efeito pragmático
Signals intent to treat the deque as a front‑insertion stack or queue.
Dica de memória
Think of adding to the front of a line of people.
Nota
deque provides O(1) appends and pops from both ends, making it suitable for queues and stacks.
Upgrade path
Consider using popleft for FIFO queue operations or rotate for rotations.
Log in to save chunks.