Python Set intersection_update() Method with Examples

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Prerequisite:

Python set() Function with Examples

Set intersection_update() Method in Python:

The intersection_update() method removes items that do not appear in both sets (or in all sets if the comparison is done between more than two sets).

The intersection_update() method differs from the intersection() method in that the former returns a new set without the unwanted items, whereas the latter removes the unwanted items from the original set.

Syntax:

set.intersection_update(set1, set2,.....)

Parameters

set1: This is Required. The set to look for items that are similar in

set2: This is Optional. The other set to look for similar items in. You are free to compare as many sets as you want. Use a comma to separate the sets.

Return Value:

None is returned by this method (meaning it does not have a return value). It only calls the intersection_update() method to update the set.

Let P, Q, R be three sets

When you execute the code,

  • the end result will be None
  • P will be updated to the intersection of P, Q, and R.
  • Q does not change.
  • R remains constant.

Examples:

Example1:

Note: Here we are updating the third set.

Input:

Given first set =  {10, 20, 30, 40, 50}
Given second set = {100, 20, 80, 70, 30}
Given third set = {200, 20, 80, 30}

Output:

The given first set is : {40, 10, 50, 20, 30}
The given second set is : {100, 70, 80, 20, 30}
The given third set is : {20, 30}
The result after applying intersection_update() method:  None

Explanation:

Here {20,30} are only the common elements in all the three sets.
Hence we are updating the third set as {20, 30}

Example2:

Note: Here we are updating the first set.

Input:

Given first set =  {'a', 'b', 'c'}
Given second set = {'b', 'p', 'q'}

Output:

The given first set is : {'b'}
The given second set is : {'p', 'q', 'b'}
The result after applying intersection_update() method:  None

Set intersection_update() Method with Examples in Python

Method #1: Using Built-in Functions (Static Input)

Approach:

  • Give the first set as static input and store it in a variable.
  • Give the second set as static input and store it in another variable.
  • Give the third set as static input and store it in another variable.
  • Apply the intersection_update() method to the given first, second and third sets.
  • Store it in another variable.
  • Print the given first set.
  • Print the given second set.
  • Print the given third set.
  • Print the above result after applying the intersection_update() method for the given three sets.
  • The Exit of the Program.

Below is the implementation:

# Give the first set as static input and store it in a variable.
fst_set = {10, 20, 30, 40, 50}
# Give the second set as static input and store it in another variable.
scnd_set = {100, 20, 80, 70, 30}
# Give the third set as static input and store it in another variable.
thrd_set = {200, 20, 80, 30}
# Apply the intersection_update() method to the given first, second and third
# sets.
# Store it in another variable.
rslt = thrd_set.intersection_update(fst_set, scnd_set)
# print the given first set.
print("The given first set is :", fst_set)
# print the given second set.
print("The given second set is :", scnd_set)
# print the given third set.
print("The given third set is :", thrd_set)
# Print the above result after applying intersection_update() method for the
# given three sets.
print("The result after applying intersection_update() method: ", rslt)

Output:

The given first set is : {40, 10, 50, 20, 30}
The given second set is : {100, 70, 80, 20, 30}
The given third set is : {20, 30}
The result after applying intersection_update() method:  None
Similarly, do the same for only two sets
# Give the first set as static input and store it in a variable.
fst_set = {'a', 'b', 'c'}
# Give the second set as static input and store it in another variable.
scnd_set = {'b', 'p', 'q'}
# Apply the intersection_update() method to the given first and second sets.
# Store it in another variable.
rslt = fst_set.intersection_update(scnd_set)
# print the given first set.
print("The given first set is :", fst_set)
# print the given second set.
print("The given second set is :", scnd_set)
# Print the above result after applying intersection_update() method for the
# given two sets.
print("The result after applying intersection_update() method: ", rslt)

Output:

The given first set is : {'b'}
The given second set is : {'p', 'q', 'b'}
The result after applying intersection_update() method:  None

Method #2: Using Built-in Functions (User Input)

Approach:

  • Give the first set as user input using set(),map(),input(),and split() functions.
  • Store it in a variable.
  • Give the second set as user input using set(),map(),input(),and split() functions.
  • Store it in another variable.
  • Give the third set as user input using set(),map(),input(),and split() functions.
  • Store it in another variable.
  • Apply the intersection_update() method to the given first, second and third sets.
  • Store it in another variable.
  • Print the given first set.
  • Print the given second set.
  • Print the given third set.
  • Print the above result after applying the intersection_update() method for the given three sets.
  • The Exit of the Program.

Below is the implementation:

# Give the first set as user input using set(),map(),input(),and split() functions.
# Store it in a variable.
fst_set = set(map(int, input(
   'Enter some random Set Elements separated by spaces = ').split()))
# Give the second set as user input using set(),map(),input(),and split() functions.
# Store it in another variable.
scnd_set = set(map(int, input(
   'Enter some random Set Elements separated by spaces = ').split()))
# Give the third set as user input using set(),map(),input(),and split() functions.
# Store it in another variable.
thrd_set = set(map(int, input(
   'Enter some random Set Elements separated by spaces = ').split()))
   
# Apply the intersection_update() method to the given first, second and third
# sets.
# Store it in another variable.
rslt = thrd_set.intersection_update(fst_set, scnd_set)
# print the given first set.
print("The given first set is :", fst_set)
# print the given second set.
print("The given second set is :", scnd_set)
# print the given third set.
print("The given third set is :", thrd_set)
# Print the above result after applying intersection_update() method for the
# given three sets.
print("The result after applying intersection_update() method: ", rslt)

Output:

Enter some random Set Elements separated by spaces = 1 8 9
Enter some random Set Elements separated by spaces = 2 9 4
Enter some random Set Elements separated by spaces = 9 4 1
The given first set is : {8, 1, 9}
The given second set is : {9, 2, 4}
The given third set is : {9}
The result after applying intersection_update() method: None