tuple

Properties

>>> dir(tuple)
['__add__', '__class__', '__class_getitem__', '__contains__', '__delattr__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__getnewargs__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__iter__', '__le__', '__len__', '__lt__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__rmul__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', 'count', 'index']

Definition

A tuple is an immutable ordered collection of items, defined with parentheses () or commas. Tuples can contain mixed types and nesting. Once created, a tuple cannot be modified; all operations that would change contents must produce a new tuple.

>>> t = (1, "a", True)
>>> t
(1, 'a', True)

>>> nested = (1, (2, 3), ["mutable list"])

Using tuples

Instantiation

# literal with parentheses
>>> t = (1, 2, 3)

# parentheses optional for simple tuples
>>> t = 1, 2, 3

# single-element tuple needs a trailing comma
>>> single = (42,)
>>> type(single)
<class 'tuple'>

# constructor from iterable
>>> tuple([1, 2, 3])
(1, 2, 3)

Accessing elements

Tuples are indexed from 0. Negative indices access from the end.

>>> t = ('apple', 2, True, 'string cheese')
>>> t[0]
'apple'
>>> t[1]
2
>>> t[-1]
'string cheese'
>>> t[-2]
True

Slicing

Tuples support slicing like lists.

>>> t = ('apple', 2, True, 'string cheese')
>>> t[0:3]
('apple', 2, True)
>>> t[1:]
(2, True, 'string cheese')
>>> t[:2]
('apple', 2)
>>> t[::2]
('apple', True)

Membership testing

Check existence with in.

>>> 2 in (1, 2, 3)
True
>>> "x" in (1, 2, 3)
False

Immutability

Tuples cannot be changed after creation.

>>> t = (1, 2, 3)
>>> t[0] = 99
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'tuple' object does not support item assignment

To “modify,” create a new tuple:

>>> t = (1, 2, 3)
>>> t = (99,) + t[1:]
>>> t
(99, 2, 3)

Packing and unpacking

>>> point = (3, 4)
>>> x, y = point
>>> x
3
>>> y
4

# extended unpacking
>>> a, *rest = (1, 2, 3, 4)
>>> a, rest
(1, [2, 3, 4])

Tuple vs list

• Tuple: immutable, typically used for fixed-size, heterogeneous data.
• List: mutable, used for sequences that change.

Dunder methods

Dunder Method	Operation	Example (normal syntax)	Example (dunder call)
__getitem__	Indexing	(1,2,3)[0] → 1	(1,2,3).__getitem__(0)
__len__	Length	len((1,2,3))	(1,2,3).__len__()
__contains__	Membership	2 in (1,2,3)	(1,2,3).__contains__(2)
__add__	Concatenation	(1,2)+(3,4) → (1,2,3,4)	(1,2).__add__((3,4))
__mul__	Repeat	(1,2)*2 → (1,2,1,2)	(1,2).__mul__(2)
__eq__	Equality	(1,2)==(1,2)	(1,2).__eq__((1,2))
__iter__	Iteration	for x in (1,2,3)	(1,2,3).__iter__()

---

tuple methods

count

Returns the number of occurrences of a value in the tuple.

>>> t = (1, 2, 2, 3)
>>> t.count(2)
2
>>> t.count(5)
0

---

index

Returns the index of the first occurrence of a value. Raises ValueError if not found.

>>> t = ('a', 'b', 'c', 'b')
>>> t.index('b')
1

>>> t.index('x')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: tuple.index(x): x not in tuple