Python Bubble Sort
last modified March 8, 2025
In this article, we explain the Bubble Sort algorithm in Python. We cover sorting numeric and textual data in ascending and descending order. We also compare Bubble Sort with Quick Sort and perform a benchmark.
An algorithm is a step-by-step procedure to solve a problem or perform a computation. Algorithms are fundamental to computer science and programming.
Sorting is the process of arranging data in a specific order, such as ascending or descending. Sorting is a common operation in programming and is used in various applications.
Common Sorting Algorithms
Some common sorting algorithms include:
- Bubble Sort
- Quick Sort
- Merge Sort
- Insertion Sort
- Selection Sort
Bubble Sort Algorithm
Bubble Sort is a simple sorting algorithm that repeatedly steps through the list, compares adjacent elements, and swaps them if they are in the wrong order. The pass through the list is repeated until the list is sorted.
Bubble Sort Example
The following is a Python implementation of the Bubble Sort algorithm.
def bubble_sort(arr):
n = len(arr)
for i in range(n):
for j in range(0, n-i-1):
if arr[j] > arr[j+1]:
arr[j], arr[j+1] = arr[j+1], arr[j]
# Example usage
nums = [64, 34, 25, 12, 22, 11, 90]
bubble_sort(nums)
print("Sorted array:", nums)
The example sorts a list of numbers in ascending order using Bubble Sort.
$ ./bubble_sort.py Sorted array: [11, 12, 22, 25, 34, 64, 90]
Sorting Textual Data
Bubble Sort can also be used to sort textual data. The following example sorts a list of strings in ascending and descending order.
def bubble_sort(arr, reverse=False):
n = len(arr)
for i in range(n):
for j in range(0, n-i-1):
if (arr[j] > arr[j+1] and not reverse) or (arr[j] < arr[j+1] and reverse):
arr[j], arr[j+1] = arr[j+1], arr[j]
# Example usage
words = ["banana", "apple", "cherry", "date"]
bubble_sort(words)
print("Sorted in ascending order:", words)
bubble_sort(words, reverse=True)
print("Sorted in descending order:", words)
The example sorts a list of words in both ascending and descending order.
$ ./bubble_sort_text.py Sorted in ascending order: ['apple', 'banana', 'cherry', 'date'] Sorted in descending order: ['date', 'cherry', 'banana', 'apple']
Comparing Bubble Sort with Quick Sort
Bubble Sort is simple but inefficient for large datasets. Quick Sort is more efficient and widely used. The following example compares the performance of Bubble Sort and Quick Sort.
import time
import random
def bubble_sort(arr):
n = len(arr)
for i in range(n):
for j in range(0, n-i-1):
if arr[j] > arr[j+1]:
arr[j], arr[j+1] = arr[j+1], arr[j]
def quick_sort(arr):
if len(arr) <= 1:
return arr
pivot = arr[len(arr) // 2]
left = [x for x in arr if x < pivot]
middle = [x for x in arr if x == pivot]
right = [x for x in arr if x > pivot]
return quick_sort(left) + middle + quick_sort(right)
# Generate a large list of random numbers
data = [random.randint(0, 1000) for _ in range(1000)]
# Benchmark Bubble Sort
start_time = time.time()
bubble_sort(data.copy())
bubble_time = time.time() - start_time
# Benchmark Quick Sort
start_time = time.time()
quick_sort(data.copy())
quick_time = time.time() - start_time
print(f"Bubble Sort time: {bubble_time:.6f} seconds")
print(f"Quick Sort time: {quick_time:.6f} seconds")
The example benchmarks Bubble Sort and Quick Sort on a list of 1000 random numbers.
Bubble Sort is a simple sorting algorithm but is inefficient for large datasets. Quick Sort is more efficient and is preferred for practical applications. Understanding sorting algorithms is essential for writing efficient programs.
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In this article, we have explained the Bubble Sort algorithm in Python.
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