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for idx in range(len(sequence)):
Iteration Patterns

Meaning

Iterates over a sequence by index, allowing you to access or modify elements using their position. Use when you need the numeric index for each iteration, such as when updating the original container or synchronising multiple sequences.

Primary Function

Indexed looping

Communicative Purpose

Provide a way to traverse a collection while exposing the element's position

Pattern

for index in range(len(sequence)):

Core Structure

for ... in range(len(...)):

Função primária

Indexed looping

Propósito comunicativo

Provide a way to traverse a collection while exposing the element's position

Situações de gatilho

Data processing: updating list elements in place; Text analysis: aligning tokens with their positions; Parallel computation: iterating over two equal-length sequences simultaneously

Contextos

General‑purpose Python scripts, data‑processing pipelines, educational examples, legacy codebases

Padrão

for index in range(len(sequence)):

Estrutura central

for ... in range(len(...)):

Slots de substituição

index_var: identifier, sequence: iterable

Colocados típicos

  • enumerate
  • zip
  • list comprehension
  • len()

Substituições comuns

  • Use enumerate loop instead of manual indexing.

Erros comuns

Using the index when direct iteration would suffice, off‑by‑one errors, modifying the sequence length during iteration

Similar / contraste

for item in sequence: – iterates directly without exposing an index; enumerate version – more Pythonic and avoids manual length calls

Interferências

Coming from C/Java, developers may overuse this pattern even when direct iteration is clearer, leading to less idiomatic Python code

Família do chunk

  • looping
  • indexing
  • iteration

Nuance

Prefer enumerate for readability; range(len) is useful when you need the index alone or when working with mutable sequences where item assignment is required

Efeito pragmático

Enables indexed access but can obscure intent compared to enumerate; may introduce off‑by‑one bugs if misused

Dica de memória

“Index loop via range‑len”

Nota

Prefer enumerate for readability; this pattern is useful when only the index is needed or when modifying the list in place.

Upgrade path

for idx, item in enumerate(sequence):

Frequência: Very highFormulaicidade: Semi-fixedTipo de construção: indexed for loopPrioridade de aquisição: Recognition firstPrioridade de output: BothTag de espaçamento: Immediate

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