Useful set functions in Python

The previous article introduced the concept of sets. This article explores useful set functions associated with accessing, adding and removing elements from a set. Some of these are the same as used for manipulating lists, while others are unique to only sets.

Determining the length of a set

The length of a set is the total number of elements in a set. The syntax to determine the length of a set is len(set). This function is also used to determine the lengths of strings and lists.

a = {1,2,3,4,5}
print(len(a))

#OUTPUT
5

Checking membership in a set

Checking membership in a set is a conditional method to determine whether a specific element occurs in a set. There are 2 operators; element in set and element not in set to check the occurrence of an element in a set.

a = {1,2,3,4,5}
print(3 in a)

#OUTPUT
True

a = {1,2,3,4,5}
print(6 not in a)

#OUTPUT
True

Two set functions to add new elements

New elements can be added to sets using the syntax set.add(newElement).

a = {1,2,3,4,5}
a.add(6)
print(a)

#OUTPUT
{1, 2, 3, 4, 5, 6}

To add multiple elements use set.update()

a = {1,2,3,4,5}
a.update({6,7,8})
print(a)

#OUTPUT
{1, 2, 3, 4, 5, 6, 7, 8}

Similarly, other data types such as strings, lists, tuples and dictionaries can also be added. There is no need of converting other data types to sets in order to use this function.

Three set functions to eliminate set elements

The set.clear() function is used to remove all the elements from a set.

a = {1,2,3,4,5}
a.clear()
print(a)

#OUTPUT
set()

To clear specific elements from a set use set.discard(element)

a = {1,2,3,4,5}
a.discard(5)
print(a)

#OUTPUT
{1, 2, 3, 4}

Similarly, set.remove(element) can also be used to eliminate set elements.

a = {1,2,3,4,5}
a.remove(5)
print(a)

#OUTPUT
{1, 2, 3, 4}