Python Tuples

A tuple is an ordered collection that cannot be changed after it is created. Use tuples for fixed groups of values, such as coordinates, RGB colours or a database row, and to return several values from a function.

Create a tuple

Write items separated by commas, usually inside round brackets.

point = (12.5, 77.3)rgb = (255, 128, 0)mixed = ("Asha", 29, True)empty = () print(point, type(point).__name__)print(len(mixed), len(empty))

(12.5, 77.3) tuple
3 0

The commas make the tuple, not the brackets. You can even leave the brackets out:

version = 3, 12, 1print(version)

(3, 12, 1)

The one-item trap

A single value in brackets is just that value. Add a trailing comma to make a one-item tuple:

not_a_tuple = (5)one_item = (5,)print(type(not_a_tuple).__name__, type(one_item).__name__)

int tuple

Access items

Indexing and slicing work exactly as with lists and strings, and a slice of a tuple is a new tuple.

days = ("Mon", "Tue", "Wed", "Thu", "Fri")print(days[0], days[-1])print(days[1:4])print("Wed" in days) for i, day in enumerate(days, 1):    print(i, day, end="  ")

Mon Fri
('Tue', 'Wed', 'Thu')
True
1 Mon  2 Tue  3 Wed  4 Thu  5 Fri  

Tuples are immutable

You cannot add, remove or replace items. Trying to raises a TypeError:

rgb = (255, 128, 0)rgb[0] = 200

Traceback (most recent call last):
  File "main.py", line 2, in <module>
    rgb[0] = 200
    ~~~^^^
TypeError: 'tuple' object does not support item assignment

To “change” a tuple, build a new one:

rgb = (255, 128, 0)rgb = (200,) + rgb[1:]print(rgb)print(rgb * 2)

(200, 128, 0)
(200, 128, 0, 200, 128, 0)

Unpacking

Assign a tuple’s items to several names in one step. This is used everywhere in Python.

name, age, city = ("Ravi", 31, "Pune")print(name, age, city) first, *middle, last = (1, 2, 3, 4, 5)print(first, middle, last) def min_max(values):    return min(values), max(values)      # returns a tuple low, high = min_max([7, 2, 9, 4])print(low, high)

Ravi 31 Pune
1 [2, 3, 4] 5
2 9

Tuple methods

Because tuples cannot change, they have only two methods:

marks = (90, 75, 90, 60, 90)print(marks.count(90))print(marks.index(75))print(sorted(marks), min(marks), max(marks), sum(marks))

3
1
[60, 75, 90, 90, 90] 60 90 405

Tuples as dictionary keys

Tuples can be dictionary keys and set members because they are immutable (and hashable). Lists cannot.

distances = {("Pune", "Mumbai"): 150, ("Pune", "Nashik"): 210}print(distances[("Pune", "Mumbai")])

150

bad = {["Pune", "Mumbai"]: 150}

Traceback (most recent call last):
  File "main.py", line 1, in <module>
    bad = {["Pune", "Mumbai"]: 150}
          ^^^^^^^^^^^^^^^^^^^^^^^^^
TypeError: cannot use 'list' as a dict key (unhashable type: 'list')

Named tuples

collections.namedtuple gives each position a name, so code reads p.x instead of p[0]:

from collections import namedtuple Point = namedtuple("Point", ["x", "y"])p = Point(3, 4)print(p)print(p.x, p.y, p[0])

Point(x=3, y=4)
3 4 3

Check your understanding

t = (1, [2, 3], 4)t[1].append(99)print(t, len(t))

(1, [2, 3, 99], 4) 3

[("Asha", 88), ("Ravi", 74), ("Meena", 93)]

Topper: Meena 93
Average: 85.0

records = [("Asha", 88), ("Ravi", 74), ("Meena", 93)] total = 0for name, marks in records:    total += marks top_name, top_marks = max(records, key=lambda r: r[1])print("Topper:", top_name, top_marks)print("Average:", round(total / len(records), 2))

Topper: Meena 93
Average: 85.0

Program Practice

Python tuples FAQ