What is a Tuple?

15 min · Beginner

A tuple is an ordered group of values that cannot be changed after it is made. Use it for a small, fixed record, such as a product or a point on a map.

Making a tuple

Tuple is an ordered group of values written in round brackets, such as (4, 9). Items keep their position, can be of any type, and cannot be changed after the tuple is created.

A fixed record, such as a product with a name, a price and a stock count, needs a safe home. A tuple keeps values in order, written inside round brackets.

Python

1product = ("Keyboard", 49.5, 3)2print(product[0])3print(product[-1])4print(len(product))5single = (7,)6print(type(single))7print(type((7)))

Example 1 · Storing a customer record

Python

customer = ("Asha", "Pune", 29)print(customer[0])print(len(customer))print(customer)

Output

Asha
3
('Asha', 'Pune', 29)

What this code does

customer[0] reads the first item, the name.
len(customer) counts the items.
print(customer) shows the whole tuple in round brackets.

Indexes work as in a list: 0 is the first item and -1 is the last. A one-item tuple needs a trailing comma. (7,) is a tuple, but (7) is just the number 7 in brackets.

Immutable: no changes in place

Immutable means that an object cannot be changed after it is created. Tuples, strings and numbers are immutable. Lists are mutable.

A list can be edited in place. A tuple cannot, so a record cannot change by accident. To get a different tuple, build a new one.

Python

1sizes = (38, 40, 42)2bigger = sizes + (44,)3print(sizes)4print(bigger)5as_list = list(sizes)6as_list[0] = 367print(tuple(as_list))

Example 2 · Building a new tuple

Python

prices = (100, 200)with_extra = prices + (300,)print(prices)print(with_extra)

Output

(100, 200)
(100, 200, 300)

What this code does

+ joins two tuples into a new one.
The old tuple prices is unchanged, because tuples cannot change.

sizes + (44,) makes a new tuple and leaves sizes alone. Writing sizes[0] = 36 would raise a TypeError, because a tuple does not allow item assignment.

Reading a tuple

Every list tool that only reads works on tuples too: loops, in, slices, count and index. Only the methods that change items, such as append, are missing.

Python

1marks = (72, 85, 72, 90)2for m in marks:3    print(m)4print(85 in marks)5print(marks.count(72))6print(marks.index(90))7print(marks[1:3])

Example 3 · Counting repeated marks

Python

marks = (72, 85, 72, 90, 72)print(marks.count(72))print(marks.index(85))print(90 in marks)

Output

3
1
True

What this code does

count(72) finds three 72s.
index(85) is 1, the position of the first 85.
in checks if a value is inside the tuple.

count(72) counts how often 72 appears. index(90) gives the position of the first 90. A slice of a tuple is a new tuple.

A tuple that holds a list

Immutable has a limit. A tuple fixes which objects it holds, not what happens inside them.

Python

order = ("A-101", ["pen", "book"])order[1].append("bag")print(order)

The tuple t = (1, [2, 3]) has two fixed slots. The second slot points to a list. The slots cannot be replaced, but the list can still change, so t[1].append(4) works and the list becomes [2, 3, 4].

The tuple still points to the same list, but that list was changed. The slots of a tuple cannot be replaced, yet a mutable object inside can still change.

Next step

Check your understanding

10 quick questions

Making a tuple

Tuple is an ordered group of values written in round brackets, such as (4, 9). Items keep their position, can be of any type, and cannot be changed after the tuple is created.

A fixed record, such as a product with a name, a price and a stock count, needs a safe home. A tuple keeps values in order, written inside round brackets.