Python Program to Find the Intersection of Two Lists

This is a Python Program to find the intersection of two lists.

The program takes two lists and finds the intersection of the two lists.

1. Define a function that accepts two lists and returns the intersection of them.
2. Declare two empty lists and initialize them to an empty list.
3. Consider a for loop to accept values for the two lists.
4. Take the number of elements in the list and store it in a variable.
5. Accept the values into the list using another for loop and insert into the list.
6. Repeat 4 and 5 for the second list also.
7. Find the intersection of the two lists.
8. Print the intersection.
9. Exit.

Here is source code of the Python Program to find the intersection of two lists. The program output is also shown below.

def intersection(a, b):
    return list(set(a) & set(b))
 
def main():
    alist=[]
    blist=[]
    n1=int(input("Enter number of elements for list1:"))
    n2=int(input("Enter number of elements for list2:"))
    print("For list1:")
    for x in range(0,n1):
        element=int(input("Enter element" + str(x+1) + ":"))
        alist.append(element)
    print("For list2:")
    for x in range(0,n2):
        element=int(input("Enter element" + str(x+1) + ":"))
        blist.append(element)
    print("The intersection is :")
    print(intersection(alist, blist))
main()

1. User must enter the number of elements in the list and store it in a variable.
2. User must enter the values to the same number of elements into the list.
3. The append function obtains each element from the user and adds the same to the end of the list as many times as the number of elements taken.
4. The same of 2 and 3 is done for the second list also.
5. The intersection function accepts two lists and returns the list which is the intersection of the two lists, i.e, all the common values from list 1 and 2.
6. The set function in the intersection function accepts a list and returns the list which contains the common elements in both the lists.
7. The lists are passed to the intersection function and the returned list is printed.

 
Case 1:
Enter number of elements for list1:3
Enter number of elements for list2:4
For list1:
Enter element1:34
Enter element2:23
Enter element3:65
For list2:
Enter element1:33
Enter element2:65
Enter element3:23
Enter element4:86
The intersection is :
[65, 23]
 
Case 2:
Enter number of elements for list1:2
Enter number of elements for list2:4
For list1:
Enter element1:3
Enter element2:4
For list2:
Enter element1:12
Enter element2:34
Enter element3:4
Enter element4:6
The intersection is :
[4]

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