Python/sorts/insertion_sort.py

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"""
A pure Python implementation of the insertion sort algorithm
This algorithm sorts a collection by comparing adjacent elements.
When it finds that order is not respected, it moves the element compared
backward until the order is correct. It then goes back directly to the
element's initial position resuming forward comparison.
For doctests run following command:
python3 -m doctest -v insertion_sort.py
For manual testing run:
python3 insertion_sort.py
"""
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from collections.abc import MutableSequence
from typing import Any, Protocol, TypeVar
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class Comparable(Protocol):
def __lt__(self, other: Any, /) -> bool: ...
T = TypeVar("T", bound=Comparable)
def insertion_sort(collection: MutableSequence[T]) -> MutableSequence[T]:
"""A pure Python implementation of the insertion sort algorithm
:param collection: some mutable ordered collection with heterogeneous
comparable items inside
:return: the same collection ordered by ascending
Examples:
>>> insertion_sort([0, 5, 3, 2, 2])
[0, 2, 2, 3, 5]
>>> insertion_sort([]) == sorted([])
True
>>> insertion_sort([-2, -5, -45]) == sorted([-2, -5, -45])
True
>>> insertion_sort(['d', 'a', 'b', 'e', 'c']) == sorted(['d', 'a', 'b', 'e', 'c'])
True
>>> import random
>>> collection = random.sample(range(-50, 50), 100)
>>> insertion_sort(collection) == sorted(collection)
True
>>> import string
>>> collection = random.choices(string.ascii_letters + string.digits, k=100)
>>> insertion_sort(collection) == sorted(collection)
True
"""
for insert_index in range(1, len(collection)):
insert_value = collection[insert_index]
while insert_index > 0 and insert_value < collection[insert_index - 1]:
collection[insert_index] = collection[insert_index - 1]
insert_index -= 1
collection[insert_index] = insert_value
return collection
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if __name__ == "__main__":
from doctest import testmod
testmod()
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user_input = input("Enter numbers separated by a comma:\n").strip()
unsorted = [int(item) for item in user_input.split(",")]
print(f"{insertion_sort(unsorted) = }")