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How to add an element to a set in Python (in 4 ways)

How to add an element to a list in Python

In this tutorial we will learn how to add an element to a set in Python . We will do it using 4 ways . They are as follows –

  • Python Set add() method
  • Python Set update() method
  • Python Set update(|=) operator .
  • Python Set union(|) operator

Let us have a look about all this ways with examples –

Python Set add() method

It adds an element to the given set . The element must be of a hashable type .

Syntax of add() method

set.add(element)

Parameters of add() method

  • element = It is a hashable type python object which will be added to the given set .

Return type of add() method

It returns None .

Examples of Python Set add() method

Example 1: Add an integer to a set

# declaring a set
myset={1,3,4,8 ,9}

# add 7 to the set
myset.add(7)

# printing the set
print(myset)
{1, 3, 4, 7, 8, 9}
  • In the above code first we have declared a set named myset as {1,3,4,8 ,9} .
  • Then we have added an integer 7 with the set using add() method .
  • From the output we can see that 7 is added to the set . As set is unordered so 7 can be added to any place in the set .

Example 2: Add a tuple to a set

# declaring a set
myset={1,3,4,8 ,9}

# add a tuple to the set
myset.add((8,9))

# printing the set
print(myset)
{1, 3, 4, (8, 9), 8, 9}

In the above code we have added a tuple to a set .

Note :

As list , set , dictionary are not a hashable type Python object so if we try to add list , set , dictionary to a set then it will raise TypeError .

Example : Try to add unhashable object to a set

# declaring a set
myset={1,3,4,8 ,9}

# add a list to the set
myset.add([8,9])  # error

# add a dictionary to the set
myset.add({8:1,9:1})  # error

# add a set to the set
myset.add({8,9})  #error
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
C:\Users\RAJKUM~1\AppData\Local\Temp/ipykernel_8720/3787350739.py in <module>
      3 
      4 # add a list to the set
----> 5 myset.add([8,9])  # error
      6 
      7 # add a dictionary to the set

TypeError: unhashable type: 'list'

Python Set update() method

It adds multiple elements from one or more iterables to the given set . The elements of the iterables must be of a hashable type .

Syntax of update() method

set.update(iterables)

Parameters of update() method

  • iterables = One or more Python iterables that should contain only hashable type element .

Return type of update() method

It returns None .

Examples of Python Set update() method

Example 1: Add elements from an iterable to a set

# declaring a set
myset={1,2,3,4}

# add elements from an iterables to the set
myset.update((8,9))

# printing the set
print(myset)
{1, 2, 3, 4, 8, 9}
  • In the above code first we have declared a set named myset as {1,2,3,4} .
  • Then we have added elements from an iterable (8,9) to the set using update() method .
  • From the output we can see that each element from the iterable is added to the set .

Example 2: Add elements from multiple iterables to a set

# declaring a set
myset={1,2,3,4}

# add elements from multiple iterables to the set
myset.update((8,9),{5,6},[11,12])

# printing the set
print(myset)
{1, 2, 3, 4, 5, 6, 8, 9, 11, 12}

In the above code we have added multiple elements from various type iterables to the given set .

Python Set update(|=) operator

It adds elements from a set to the given set .

Syntax of update(|=) operator

set|=other

Parameters of update(|=) operator

  • other = It is a set or an expression that can be evaluate to a set .

Return type of update(|=) operator

It returns None .

Examples of Python Set update(|=) operator

Example 1: Merge two sets in Python

# declaring a set
myset={1,2,3,4}

# adding elements
myset|= {5,6,7}

# printion the set
print(myset)
{1, 2, 3, 4, 5, 6, 7}

In the above code we have added a set {1,2,3,4} with an other set {5,6,7} using update(|=) operator .

Example 2: 

# declaring a set
myset={1,2,3,4}

# adding elements
myset|= {item for item in range(5,8)}

# printing the set
print(myset)
{1, 2, 3, 4, 5, 6, 7}

In the above code we have added a set {1,2,3,4} with a set comprehension using update(|=) operator .

Python Set union (|) operator

It returns a new set after adding elements from two set .

Syntax of union(|) operator

set|other

Parameters of union(|) operator

  • other = It is a set or an expression that can be evaluate to a set .

Return type of union(|) operator

It returns a set .

Examples of Python Set union(|) operator

Example 1: Merge two sets in Python

# declaring two set
myset1={1,2,3,4}
myset2={5,6,7}

# adding elements of two sets
myset = myset1 | myset2

# printing the set
print(myset)
{1, 2, 3, 4, 5, 6, 7}

In the above code we have added elements from two sets using union (|) operator .

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