python (optimizing) bubble sort

Question

I saw in Wikipedia (the first under Optimizing bubble sort) a pseudo-code to bubble sort and I implemented it in Python.

I am posting my implementation here because I'm new to Python, and I'm looking mostly for programming in a more pythonic way.

def bubbleSort(array):
    n = len(array)
    swapped = True
    while swapped:
        swapped = False
        for i in range(n - 1):
            if array[i] > array[i + 1]:
                array[i], array[i + 1] = array[i + 1], array[i]
                swapped = True
        n -= 1
    return array


def main():
    array = [1, 7, 4, 3, 2, 9, 8, 5, 6]
    array = bubbleSort(array)
    print(array)

if __name__ == '__main__':
    main()

I'd love to know if there are any stuff that I can optimize (syntactic-wise), like the fact that I'm writing swapped = True, and afterward changing it again, and again ... which thing annoys me.

301_Moved_Permanently · Accepted Answer · 2017-10-17 08:24:15Z

Your bubbleSort function both mutate the array in-place and return it. This is unnecessary at best, error-prone at worse since a user could think that it return a new list.

So I would remove the return statement and have the main look like:

def main():
    array = [1, 7, 4, 3, 2, 9, 8, 5, 6]
    bubbleSort(array)
    print(array)

Even better, as your main is mostly a test of bubbleSort, you could rename it as such and accept the array as parameter:

def test_bubble_sort(array):
    print(array, end=' => ')
    bubbleSort(array)
    print(array)


if __name__ == '__main__':
    test_bubble_sort([1, 7, 4, 3, 2, 9, 8, 5, 6])
    test_bubble_sort([9, 8, 7, 6, 4, 5, 2, 3, 1])

Ram Chandra Giri · Accepted Answer · 2017-10-14 02:37:37Z

5

Also a beginner but one thing I would like to point out is naming function, Style Guide for Python Code states:

Function Names
Function names should be lowercase, with words separated by underscores as necessary to improve readability.

mixedCase is allowed only in contexts where that's already the prevailing style (e.g. threading.py), to retain backwards compatibility.

So, in your case write bubble_sort instead of bubbleSort.

answered Oct 14, 2017 at 2:37

Ram Chandra Giri

3574 silver badges12 bronze badges

Add a comment |

Billal BEGUERADJ · Accepted Answer · 2017-10-17 06:55:49Z

4

like the fact that I'm writing swapped = True, and afterward changing it again, and again annoys me.

The truth is that you do not even need that swapped variable as you can simplify your function and get rid of repeated and useless instructions related to it:

def bubble_sort(array):
    n = len(array)
    while n:
        for i in range(n - 1):
            if array[i] > array[i + 1]:
                array[i], array[i + 1] = array[i + 1], array[i]
        n -= 1
    return array

def main():
   array = [1, 7, 4, 3, 2, 9, 8, 5, 6]
   array = bubble_sort(array)
   print(array)

if __name__ == '__main__':
   main()

edited Oct 17, 2017 at 6:55

answered Oct 14, 2017 at 7:18

Billal BEGUERADJ

1

2

\$\begingroup\$ Now it works. But your while loop could just be a for loop: for n in range(len(array), 0, -1). \$\endgroup\$

Graipher
– Graipher

2017-10-16 06:49:18 +00:00
Commented Oct 16, 2017 at 6:49

Add a comment |

Stack Exchange Network

python (optimizing) bubble sort

3 Answers 3

You must log in to answer this question.

Hot Network Questions

python (optimizing) bubble sort

3 Answers 3

You must log in to answer this question.

Related

Hot Network Questions