Python: Insertion Sort

Question

I am a beginner in python and to learn python I have written this program. How can this code be improved? Should I use main method in this program? Python

lst = []
def insertion_sort(thelist):
 for index in range(1, len(thelist)):
 key = thelist[index]
 position = index - 1
 while position >= 0 and thelist[position] > key:
 thelist[position + 1] = thelist[position]
 position = position - 1
 thelist[position + 1] = key
n = int(input("Enter number of elements: "))
for i in range(0, n):
 ele = int(input())
 lst.append(ele)
insertion_sort(lst)
print(*lst, sep = ", ")

Answer 1

There is a much simpler method in Python to do an insertion sort using the bisect.insort method

import bisect
array = [1,3,5,7]
bisect.insort_left(array, 2)
>>[1, 2, 3, 5, 7]

With regard to your coding style, I would recommend using the if __name__ == "__main__" guard.

You can also just say for i in range(n) with no need to say (0, n)

You can also use list-comprehension to build the list:

import bisect
def insertion_sort(thelist):
 new_list = []
 for item in thelist:
 bisect.insort_left(new_list, item)
 return new_list
if __name__ == "__main__":
 n = int(input("Enter number of elements: "))
 lst = [input("Please enter a number: ") for i in range(n)]
 new_list = insertion_sort(lst)
 print(*new_list, sep = ", ")

Answer 2

• Try to make functions for every logical thing you do like getting the elements. use def get_input()

• Use if __name__ == "__main__" guard. It is a good practice when you are importing this program to another program, it will not run the code in this program entirely.

• There is no need to use a for loop for getting the list you can use split() on the entire input which would create a list as desired. It is pythonic to use split().

• There is no need to make n as lists in python are dynamic. You can get the length in O(1) time using len(lst).

• Name your variables clearly, slightly longer names are not a problem. lst would be input_list etc.

• You can use enumerate in for index in range(1, len(thelist)):. Which would give the index and elements of the list. More pythonic.