Python Searching and Sorting|Bubble Sort

Implementation in Python Code

Program

# Creating a bubble sort function  
def bubble_sort(list1):  
    # Outer loop for traverse the entire list  
    for i in range(0,len(list1)-1):  
        for j in range(len(list1)-1):  
            if(list1[j]>list1[j+1]):  
                temp = list1[j]  
                list1[j] = list1[j+1]  
                list1[j+1] = temp  
    return list1  
  
list1 = [5, 3, 8, 6, 7, 2]  
print("The unsorted list is: ", list1)  
# Calling the bubble sort function  
print("The sorted list is: ", bubble_sort(list1))  

Output:

The unsorted list is: [5, 3, 8, 6, 7, 2]
The sorted list is: [2, 3, 5, 6, 7, 8]

Without using a temp variable

We can also swap the elements without using the temp variable. Python has a very unique syntax. We can use the following lines of code.

Example –

def bubble_sort(list1):  
    # Outer loop for traverse the entire list  
    for i in range(0,len(list1)-1):  
        for j in range(len(list1)-1):  
            if(list1[j]>list1[j+1]):   
                # here we are not using temp variable  
                list1[j],list1[j+1] = list1[j+1], list1[j]  
    return list1  
  
list1 = [5, 3, 8, 6, 7, 2]  
print("The unsorted list is: ", list1)  
# Calling the bubble sort function  
print("The sorted list is: ", bubble_sort(list1))  

Output:

The unsorted list is: [5, 3, 8, 6, 7, 2]
The sorted list is: [2, 3, 5, 6, 7, 8]

Optimization of Python Code Implementation

We can optimize the above code using the two techniques. The swaps are not done; it means list is sorted. In the previous technique – The previous technique will evaluate the complete list though it doesn’t seem necessary to do.

We can prevent the unnecessary evaluation using the Boolean flag and checks if any swaps were made in the previous section.

Example –

def bubble_sort(list1):  
   # We can stop the iteration once the swap has done  
    has_swapped = True  
  
    while(has_swapped):  
        has_swapped = False  
        for i in range(len(list1) - 1):  
            if list1[i] > list1[i+1]:  
                # Swap  
                list1[i], list1[i+1] = list1[i+1], list1[i]  
                has_swapped = True  
    return list1  
  
  
list1 = [5, 3, 8, 6, 7, 2]  
print("The unsorted list is: ", list1)  
# Calling the bubble sort function  
print("The sorted list is: ", bubble_sort(list1))  

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