Tuple Methods and Built-in Functions

Python ships with several ready-made functions and methods for working with tuples. Table 10.1 of the textbook collects the commonly used ones; each is explained below with its behaviour and a worked example.

len() — length of the tuple

Returns the length, i.e. the number of elements of the tuple passed as the argument:

>>> t = (10, 20, 30, 40, 50)
>>> len(t)
5

tuple() — creating tuples

Called with no argument, it creates an empty tuple. Called with a sequence (string, list, range, ...), it converts that sequence into a tuple:

>>> empty = tuple()
>>> empty
()

>>> vowels = tuple('aeiou')     # from a string
>>> vowels
('a', 'e', 'i', 'o', 'u')

>>> nums = tuple([1, 2, 3])     # from a list
>>> nums
(1, 2, 3)

>>> first5 = tuple(range(5))    # from a range
>>> first5
(0, 1, 2, 3, 4)

count() — occurrences of an element

Returns the number of times the given element appears in the tuple. If the element is absent, the count is simply 0 (no error):

>>> t = (10, 20, 30, 10, 40, 10, 50)
>>> t.count(10)
3
>>> t.count(90)
0

index() — position of the first occurrence

Returns the index of the first occurrence of the element. Unlike count(), asking for an element that is not present raises a ValueError:

>>> t = (10, 20, 30, 40, 50)
>>> t.index(30)
2
>>> t.index(90)
ValueError: tuple.index(x): x not in tuple

sorted() — a sorted list of the elements

Takes the elements of the tuple and returns a new sorted list. Two things to remember: the result is a list, not a tuple, and sorted() makes no change to the original tuple:

>>> names = ('Kiran', 'Asha', 'Zara', 'Dev', 'Meera') …