List Methods

Python · Methods reference

Python · Methods reference

📋 Overview

All common list instance methods plus builtins that operate on lists.

🔧 Methods

Instance methods

Method	Mutates?	Description
`append(x)`	yes	Add item at end — O(1) amortized
`extend(iterable)`	yes	Add all items from iterable
`insert(i, x)`	yes	Insert before index i — O(n)
`remove(x)`	yes	Remove first equal item; ValueError if missing
`pop([i])`	yes	Remove and return item at i (default last)
`clear()`	yes	Remove all items
`index(x[, start[, stop]])`	no	First index of x; ValueError if missing
`count(x)`	no	Count occurrences of x
`sort(*, key=None, reverse=False)`	yes	In-place sort; returns None
`reverse()`	yes	In-place reverse; returns None
`copy()`	no	Shallow copy (same as `xs[:]` / `list(xs)`)

Builtins / operators

API	Description
`len(xs)`	Number of items
`x in xs`	Membership test — O(n)
`sorted(xs, key=…)`	New sorted list
`reversed(xs)`	Reverse iterator
`min` / `max` / `sum`	Aggregates over elements
`enumerate(xs)`	Index-value pairs
`zip(*seqs)`	Parallel tuples
`del xs[i]` / slice assign	Delete or replace ranges

💡 Examples

See parent topic notes for runnable snippets; this page is the complete method index.

⚠️ Pitfalls

Mutating methods return None in Python — do not chain sort() / reverse() expecting a new list.
Default JS sort() compares strings — pass (a,b) => a-b for numbers.
SQL function names differ by dialect — verify Postgres vs MySQL docs.
Django QuerySet.update() skips save() signals and auto auto_now fields on models.

Dict Methods

Python · Methods reference

Set Methods

Python · Methods reference

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📋 Overview 🔧 Methods Instance methods Builtins / operators 💡 Examples ⚠️ Pitfalls 🔗 Related