7.2.2. Manipulating Elements

A tuple on its own is immutable meaning once it is created, the elements of it cannot be modified directly.

There are some other ways of indirectly acheiving this behaviour which will be discussed in this section.

List type casting

Tuples can be converted to a list using the list function on the tuple. This type casts the tuple into a list which can be manipulated and then reconverted into a tuple with a similar method:

CodeOutput

fruits = ('apple', 'banana', 'peach')

# convert fruits tuple to a list
fruits = list(fruits)

# modify elements (e.g. add new element)
fruits.append('strawberry')

# convert back to tuple
fruits = tuple(fruits)

# output new tuple
print(fruits)

('apple', 'banana', 'peach', 'strawberry')

In order to remove elements, methods like list.pop() or the del keyword could be used. For more information about list operations, see section 7.1.2. Lists: Manipulating Elements.

Concatenating elements (the + operator)

Two or more tuples can be concatenated using the + operator.

CodeOutput

fruits = ('apple', 'banana', 'peach')
print(fruits)

fruits = fruits + ('strawberry', 'pineapple')
print(fruits)

('apple', 'banana', 'peach')
('apple', 'banana', 'peach', 'strawberry', 'pineapple')

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Note

Both the approaches shown above to manipulate tuple elements do not change the fact that tuples are immutable.

In both cases, a new tuple is created every time that replaces the old one. The original tuple cannot be updated after its initial definition.

CodeOutput

fruits = ('apple', 'banana', 'peach')

# convert fruits tuple to a list
# and store in new_fruits
new_fruits = list(fruits)

# modify elements (e.g. add new element)
new_fruits.append('strawberry')

# convert new_fruits list to tuple
new_fruits = tuple(new_fruits)

# output new tuple
print('new:', new_fruits)

# output original tuple
print('original:', fruits)

('apple', 'banana', 'peach', 'strawberry')
('apple', 'banana', 'peach')

As you can see, the original tuple remains as-is as list(fruits) returns a completely new list and doesn't change the original tuple.

Similarly performing tup1 + tup2 returns a new tuple with elements of both tup1 and tup2 but the content of tup1 and tup2 remains the same as original.

CodeOutput

tup1 = ('a', 'b', 'c')
tup2 = ('d', 'e', 'f')
tup3 = tup1 + tup2

print(tup3)
print(tup1)
print(tup2)

('a', 'b', 'c', 'd', 'e', 'f')
('a', 'b', 'c')
('d', 'e', 'f')