Python: Heapsort

Question

I am beginner in python and I am learing about syntax and other functions in python by writing Algorithm and Data Structure programs.

How can this code be improved?

def get_input(): #to get input from user
 input_str = input("Enter elements to be sorted: ")
 try:
 lst = list(map(int, input_str.split())) #make a list of integers from input string
 except:
 raise TypeError("Please enter a list of integers only, seperated by a space!!")
 return lst
def max_heapify(thelist, lst_size, idx):
 largest = idx
 left_child = (2 * idx) + 1
 right_child = (2 * idx) + 2
 if left_child < lst_size and thelist[left_child] > thelist[largest]:
 largest = left_child
 if right_child < lst_size and thelist[right_child] > thelist[largest]:
 largest = right_child
 if largest != idx:
 thelist[idx], thelist[largest] = thelist[largest], thelist[idx]
 max_heapify(thelist, lst_size, largest)
def build_max_heap(thelist, lst_size):
 for curr_idx in range(lst_size // 2 - 1, -1, -1):
 max_heapify(thelist, lst_size, curr_idx)
def heap_sort(thelist):
 if len(thelist) == 0:
 print("Empty list!!")
 elif len(thelist) == 1:
 print("Only one element!!")
 else:
 build_max_heap(thelist, len(thelist))
 for curr_idx in range(len(thelist) -1, 0, -1):
 thelist[curr_idx], thelist[0] = thelist[0], thelist[curr_idx] #swapping
 max_heapify(thelist, curr_idx, 0)
if __name__ == '__main__':
 input_list = get_input()
 heap_sort(input_list)
 print(*input_list, sep = ", ")

• greybeard: (I neither considered seriously inspecting your Quick Sort code nor this Heapsort for the same reason: both are "not" documented/commented.) Heed the Style Guide for Python Code

Answer 1

Use standard docstrings

This comment:

to get input from user

is best placed in a docstring:

def get_input():
 """
 get input from user
 """

Consider using type hints

You're best to google this, because there's a wealth of information about it, but as an example: the idx argument would be idx: int.

Operator precedence

(2 * idx) + 1

doesn't need parens, because multiplication has stronger association than addition.

Never except:

At the least, you should write except Exception instead of except. The latter can prevent user break (Ctrl+C) from working. If possible, replace Exception with something more specific.

Use a comprehension

map is a little difficult to read. Instead, how about

lst = [int(e) for e in input_str.split()]

Variable naming

lst isn't helpful - rather than naming things based on what type they are, you should be naming them based on what they actually mean to the program - in this case, perhaps "elements".