Python Program to Swap Two Elements in a List

In this tutorial, we will learn how to swap elements in a list using Python. We’ll cover three different methods: a function, direct swapping of the first and last elements, and swapping using the pop() and insert() methods.

Method 1: Swap Two Elements in a List using Function

Here are the steps to write a Python Python Tutorial program to swap any two elements in a list using a function:

1. Declare an empty list.
2. Take the number of elements in the list and store it in a variable.
3. Use a for loop to take value one by one and insert them into the list using the append() method.
4. Accept input values from the user, which they want to swap in the list.
5. Define a function and use this formula list[pos1], list[pos2] = list[pos2], list[pos1] to swap the values.
6. Call the function and print the result.

Here’s the code:

NumList = []

# get number of elements
Number = int(input("How many elements in list: "))

# fill list with user input
for i in range(1, Number + 1):
    value = int(input("Enter the value of element %d: " % i))
    NumList.append(value)

# print list before swapping
print("List before swapping:", NumList)

# get positions of elements to swap
position1 = int(input("Enter the position of the first element to swap: "))
position2 = int(input("Enter the position of the second element to swap: "))

# define swap function
def swap_positions(list, pos1, pos2): 
    list[pos1], list[pos2] = list[pos2], list[pos1] 
    return list
  
# call swap function and print result
print("List after swapping:", swap_positions(NumList, position1-1, position2-1))

Method 2: Swap the First and Last Value of a List

Here are the steps to write a Python program to swap the first and last element in a list:

1. Declare an empty list.
2. Take the number of elements in the list and store it in a variable.
3. Use a for loop to take value one by one and insert them into the list using the append() method.
4. Swap the first and last element in the list using a temporary variable.
5. Print the result.

Here’s the code:

NumList = []

# get number of elements
Number = int(input("How many elements in list: "))

# fill list with user input
for i in range(1, Number + 1):
    value = int(input("Enter the value of element %d: " % i))
    NumList.append(value)

# print list before swapping
print("List before swapping:", NumList)

# swap first and last element
temp = NumList[0]
NumList[0] = NumList[Number-1]
NumList[Number-1] = temp

# print list after swapping
print("List after swapping:", NumList)

Method 3: Swap Two Elements in a List using Inbuilt POP() and Insert() Function

Here are the steps to write a Python program to swap any two elements in a list using the pop() and insert() methods:

1. Declare an empty list.
2. Take the number of elements in the list and store it in a variable.
3. Use a for loop to take value one by one and insert them into the list using the append() method.
4. Accept input values from the user, which they want to swap in the list.
5. Define a function and use the list.pop(pos1) and list.insert(pos2) methods to swap the values.
6. Call the function and print the result.

Here’s the code:

NumList = []

# get number of elements
Number = int(input("How many elements in list: "))

# fill list with user input
for i in range(1, Number + 1):
    value = int(input("Enter the value of element %d: " % i))
    NumList.append(value)

# print list before swapping
print("List before swapping:", NumList)

# get positions of elements to swap
position1 = int(input("Enter the position of the first element to swap: "))
position2 = int(input("Enter the position of the second element to swap: "))

# define swap function
def swap_list(list, pos1, pos2): 
    x = list.pop(pos1)    
    y = list.pop(pos2-1) 
    list.insert(pos1, y)   
    list.insert(pos2, x)   
    return list
 
# call swap function and print result
print("List after swapping:", swap_list(NumList, position1-1, position2-1))

That’s it! Now you know how to swap elements in a list using Python.