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Tuples

More precisely, we can define a sequence as a finite and ordered set of elements.

There are two types of sequences in Python: tuples and lists.

Tuple

my_tuple = (1, 2, 3)
tuples are not modifiable (we say immutable)

List

my_list = [1, 2, 3]
lists are modifiable (we say mutable)

Tuples

In mathematics, we call tuples "ordered collections of objects". More precisely, we will call n-tuple or n-tuple a collection containing n objects. You will find more information on the page Tuple - Wikipedia.
The common term in programming is the corresponding anglicism, the tuple.

  • tuple elements are placed between parentheses: (val1, val2, val3)
  • tuples are ordered, each element is associated with an index
  • tuples are not modifiable
  • tuple elements can be of different types: you can combine strings, integers, objects, in the same tuple.

Let's start with a simple example:

first_tuple = (1, 9, 42, 13, 24)

Thus, in the first_tuple variable, we have:

  • the value 1 at position 0
  • the value 9 at position 1
  • the value 42 at position 2
  • the value 13 at position 3
  • the value 24 at position 4

To access these values, we use bracket-based notation. The code below allows analyzing each element of the tuple. We notice that we can easily make different native types coexist within the same tuple.

my_tuple = (42, "cat", 12, True)

print(type(my_tuple), ":", my_tuple)
print(type(my_tuple[0]), ":", my_tuple[0])
print(type(my_tuple[1]), ":", my_tuple[1])
print(type(my_tuple[2]), ":", my_tuple[2])
print(type(my_tuple[3]), ":", my_tuple[3])
A tuple is useful in several cases: it allows a function to return multiple values, such as coordinate pairs, phone numbers, or more generally several values that are linked.

Let's take our addition() function again. We can modify it so that instead of returning the sum of the two values, it returns a tuple containing value a, value b, and finally the sum of the two. Thus, we preserve all the information: we know the sum of the two values, but we can also find out how it was calculated.

def addition(int_a, int_b):
    if type(int_a) == type(int_b) == type(1):
        return (int_a, int_b, int_a + int_b)
    else:
        return "TYPE ERROR"

print(addition(12, 8))
A tuple cannot be modified once created.
my_tuple = (1, 2, 3)
# Trying to modify an element raises an error
my_tuple[1] = 4  # This generates an error