my_list.append

Built-in Data Structures

Meaning

The list.append() method adds a single element to the end of a list, modifying the list in place. It solves the pain of repeatedly extending a list when only one item needs to be added, avoiding the overhead of creating a new list each time. You reach for it whenever you need to accumulate items sequentially, such as building a collection in a loop.

Primary Function

List manipulation

Communicative Purpose

Adds an element to the end of a list.

Pattern

lst.append(value)

Core Structure

... .append(...)

Função primária

List manipulation

Propósito comunicativo

Adds an element to the end of a list.

Situações de gatilho

Data processing: building a list of results while iterating over records; User input handling: collecting entered items into a list; Algorithm implementation: accumulating intermediate values during a computation.

Contextos

Any Python code that uses lists; data processing scripts; algorithms that accumulate results.

Padrão

lst.append(value)

Estrutura central

... .append(...)

Slots de substituição

lst: list variable; value: any object to append

Colocados típicos

list initialization
for loops
while loops
input reading

Substituições comuns

lst += [value]
lst.extend([value]) (less efficient for single item)

Erros comuns

Assigning the result of append (which returns None) to a variable; expecting a new list.

Similar / contraste

list.extend(iterable) adds each element; list.insert(index, value) inserts at position.

Interferências

Coming from languages with push/pop methods: remember append adds to end, not front.

Família do chunk

list methods
mutating sequences
accumulation patterns

Nuance

Appending a list as a single element creates a nested list; to flatten, use extend.

Efeito pragmático

Modifies the original list efficiently without creating a copy.

Dica de memória

Think of 'adding' an item to the end of a list.

Nota

Append modifies the list in place and returns None; assigning its result to a variable yields None.

Upgrade path

Use list comprehension for building lists: [expr for item in iterable]

Frequência: HighFormulaicidade: Semi-fixedTipo de construção: method callPrioridade de aquisição: Automatic productionPrioridade de output: BothTag de espaçamento: Immediate

Examples

my_list = [] my_list.append(4) print(my_list) # [4]

numbers = [] for i in range(5): numbers.append(i*i) print(numbers) # [0, 1, 4, 9, 16]

# Mistake: assuming append returns a new list new_list = my_list.append(5) # new_list is None # Correct usage: my_list.append(5) new_list = my_list.copy()