Python Tutorial (33) - Example: Swap the first and last elements in a list

Time： 2024-09-12 Column：Python views：219

Define a List and Swap the First and Last Elements

This Python code demonstrates how to define a list and swap the first and last elements of the list. Several implementations are provided, each achieving the same result.

Before Swap:

[1, 2, 3]

After Swap:

[3, 2, 1]

Example 1: Basic Swap Using a Temporary Variable

def swapList(newList):
    size = len(newList)
    
    # Swap first and last elements using a temporary variable
    temp = newList[0]
    newList[0] = newList[size - 1]
    newList[size - 1] = temp
    
    return newList

# Define the list
newList = [1, 2, 3]

# Call the function and print the result
print(swapList(newList))

Output:

[3, 2, 1]

Example 2: Pythonic Swap Using Tuple Assignment

def swapList(newList):
    
    # Swap first and last elements using tuple assignment
    newList[0], newList[-1] = newList[-1], newList[0]
    
    return newList

# Define the list
newList = [1, 2, 3]

# Call the function and print the result
print(swapList(newList))

Output:

[3, 2, 1]

Example 3: Swap Using a Tuple

def swapList(list):
    
    # Get first and last elements and swap them
    get = list[-1], list[0]
    
    list[0], list[-1] = get
    
    return list

# Define the list
newList = [1, 2, 3]

# Call the function and print the result
print(swapList(newList))

Output:

[3, 2, 1]

Explanation:

Example 1 swaps the first and last elements by using a temporary variable.
Example 2 demonstrates a more Pythonic way to swap using tuple assignment, which directly swaps the values without needing an additional variable.
Example 3 shows how to store the swapped elements in a tuple and then assign them back to their respective positions.

These implementations all result in the first and last elements of the list being swapped effectively.

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