Python program to swap two elements in a list

Given a list in Python and provided the positions of the elements, write a program to swap the two elements in the list.

Examples:

Input : List = [23, 65, 19, 90], pos1 = 1, pos2 = 3
Output : [19, 65, 23, 90]

Input : List = [1, 2, 3, 4, 5], pos1 = 2, pos2 = 5
Output : [1, 5, 3, 4, 2]

Approach #1: Simple swap

Since the positions of the elements are known, we can simply swap the positions of the elements.

# Python3 program to swap elements # at given positions    # Swap function def swapPositions(list, pos1, pos2):            list[pos1], list[pos2] = list[pos2], list[pos1]     return list    # Driver function List = [23, 65, 19, 90] pos1, pos2  = 1, 3    print(swapPositions(List, pos1-1, pos2-1))

Output:

[19, 65, 23, 90]

 
Approach #2 : Using Inbuilt list.pop() function

Pop the element at pos1 and store it in a variable. Similarly, pop the element at pos2 and store it in another variable. Now insert the two popped element at each other’s original position.

# Python3 program to swap elements # at given positions    # Swap function def swapPositions(list, pos1, pos2):            # popping both the elements from list     first_ele = list.pop(pos1)        second_ele = list.pop(pos2-1)           # inserting in each others positions     list.insert(pos1, second_ele)       list.insert(pos2, first_ele)              return list    # Driver function List = [23, 65, 19, 90] pos1, pos2  = 1, 3    print(swapPositions(List, pos1-1, pos2-1))

Output:

[19, 65, 23, 90]

 
Approach #3 : Using tuple variable

Store the element at pos1 and pos2 as a pair in a tuple variable, say get. Unpack those elements with pos2 and pos1 positions in that list. Now, both the positions in that list are swapped.

# Python3 program to swap elements at # given positions    # Swap function def swapPositions(list, pos1, pos2):        # Storing the two elements     # as a pair in a tuple variable get     get = list[pos1], list[pos2]             # unpacking those elements     list[pos2], list[pos1] = get             return list    # Driver Code List = [23, 65, 19, 90]    pos1, pos2  = 1, 3 print(swapPositions(List, pos1-1, pos2-1))

Output:

[19, 65, 23, 90]

Approach #4 : Using comma assignment

# Python3 program to swap elements # at given positions    def swapPositions(list, pos1, pos2):     list[pos1],list[pos2] = list[pos2],list[pos1]     return list    # Driver Code List = [23, 65, 19, 90] pos1, pos2  = 1, 3 print(swapPositions(List, pos1-1, pos2-1))

Output:

[19, 65, 23, 90]