Python Tuples

Tuples

Tuples are used to store multiple items in a single variable.

Tuple is one of 4 built-in data types in Python used to store collections of data, the other 3 are List, Set, and Dictionary, all with different qualities and usage.

A tuple is a collection which is ordered and unchangeable.

Tuples are written with round brackets.

thistuple = ("apple", "banana", "cherry")
print(thistuple)

Tuple Items

Tuple items are ordered, unchangeable, and allow duplicate values.

Tuple items are indexed, the first item has index [0], the second item has index [1] etc.

Ordered

When we say that tuples are ordered, it means that the items have a defined order, and that order will not change.

Unchangeable

Tuples are unchangeable, meaning that we cannot change, add or remove items after the tuple has been created.

Allow Duplicates

Since tuples are indexed, they can have items with the same value:

thistuple = ("apple", "banana", "cherry", "apple", "cherry")
print(thistuple)

Tuple Length

To determine how many items a tuple has, use the len() function:

thistuple = ("apple", "banana", "cherry")
print(len(thistuple))

Create Tuple With One Item

To create a tuple with only one item, you have to add a comma after the item, otherwise Python will not recognize it as a tuple.

thistuple = ("apple",)
print(type(thistuple))

# NOT a tuple
thistuple = ("apple")
print(type(thistuple))

Tuple Items - Data Types

Tuple items can be of any data type:

tuple1 = ("apple", "banana", "cherry")
tuple2 = (1, 5, 7, 9, 3)
tuple3 = (True, False, False)

A tuple can contain different data types:

tuple1 = ("abc", 34, True, 40, "male")

type()

From Python's perspective, tuples are defined as objects with the data type 'tuple':

mytuple = ("apple", "banana", "cherry")
print(type(mytuple))

The tuple() Constructor

It is also possible to use the tuple() constructor to make a tuple.

thistuple = tuple(("apple", "banana", "cherry")) # note the double round-brackets
print(thistuple)

Access Tuple Items

You can access tuple items by referring to the index number, inside square brackets:

thistuple = ("apple", "banana", "cherry")
print(thistuple[1])

Negative Indexing

Negative indexing means start from the end.

-1 refers to the last item, -2 refers to the second last item etc.

thistuple = ("apple", "banana", "cherry")
print(thistuple[-1])

Range of Indexes

You can specify a range of indexes by specifying where to start and where to end the range.

When specifying a range, the return value will be a new tuple with the specified items.

thistuple = ("apple", "banana", "cherry", "orange", "kiwi", "melon", "mango")
print(thistuple[2:5])

Update Tuples

Tuples are unchangeable, meaning that you cannot change, add, or remove items once the tuple is created.

But there are some workarounds.

Change Tuple Values

Once a tuple is created, you cannot change its values. Tuples are unchangeable, or immutable as it also is called.

But there is a workaround. You can convert the tuple into a list, change the list, and convert the list back into a tuple.

x = ("apple", "banana", "cherry")
y = list(x)
y[1] = "kiwi"
x = tuple(y)

print(x)

Add Items

Since tuples are immutable, they do not have a built-in append() method, but there are other ways to add items to a tuple.

1. Convert into a list: Just like the workaround for changing a tuple, you can convert it into a list, add your item(s), and convert it back into a tuple.

thistuple = ("apple", "banana", "cherry")
y = list(thistuple)
y.append("orange")
thistuple = tuple(y)

2. Add tuple to a tuple. You are allowed to add tuples to tuples, so if you want to add one item, (or many), create a new tuple with the item(s), and add it to the existing tuple:

thistuple = ("apple", "banana", "cherry")
y = ("orange",)
thistuple += y

print(thistuple)

Unpack Tuples

When we create a tuple, we normally assign values to it. This is called "packing" a tuple:

fruits = ("apple", "banana", "cherry")

But, in Python, we are also allowed to extract the values back into variables. This is called "unpacking":

fruits = ("apple", "banana", "cherry")

(green, yellow, red) = fruits

print(green)
print(yellow)
print(red)

Note: The number of variables must match the number of values in the tuple, if not, you must use an asterisk to collect the remaining values as a list.

Using Asterisk*

If the number of variables is less than the number of values, you can add an * to the variable name and the values will be assigned to the variable as a list:

fruits = ("apple", "banana", "cherry", "strawberry", "raspberry")

(green, yellow, *red) = fruits

print(green)
print(yellow)
print(red)