Quick Sort implementation in python

Question

Implemented the quick sort algorithm in python, It was just for learning it, now I want to port it to C.

Thoughts on the quality of my python implementation?

from random import randint, shuffle
def swap(array, a, b):
 array[a], array[b] = array[b], array[a]
def quick_sort(array, start=0, end=None):
 if end is None:
 end = len(array) - 1
 if end - start >= 1:
 pivot = array[end]
 a = start
 b = end - 1
 while not a > b:
 if not array[a] > pivot:
 a += 1
 continue
 else:
 if array[b] < pivot:
 swap(array, a, b)
 a += 1
 b -= 1
 swap(array, a, end)
 quick_sort(array, start, a - 1)
 quick_sort(array, a + 1, end)
arr = [randint(0, 30) for _ in range(20)]
print(arr)
quick_sort(arr)
print(arr)

• StackOverflowToxicityVictim: It works, so far, I didn't found any error.
• markspace: OK, just checking.

Answer 1

Magic Numbers

arr = [randint(0, 30) for _ in range(20)]

What are 0, 30, and 20 supposed to represent? I would assign these to variables to make it more clear

Type Hints

This

def swap(array, a, b):

can be this

def swap(array: list, a: int, b: int) -> None:

These allow you to show what types of parameters are accepted, and what types are returned from the functions.

Main Guard

This

arr = [randint(0, 30) for _ in range(20)]
print(arr)
quick_sort(arr)
print(arr)

should be put in a main guard, like so

if __name__ == '__main__':
 arr = [randint(0, 30) for _ in range(20)]
 print(arr)
 quick_sort(arr)
 print(arr)

This prevents this code from running if you decide to import this module from another module/program.