# ------------------------------------------------------------
# A small program demonstrating how to remove every Nth element
# from a list using clear, expressive Python patterns.
# ------------------------------------------------------------
from typing import List, Any
def remove_every_nth(items: List[Any], n: int) -> List[Any]:
"""
Return a new list with every n-th element removed.
The function uses enumerate to pair each element with its index.
Because enumerate starts at 0, we check (index + 1) % n == 0
to identify positions that should be removed.
List comprehensions provide a concise and efficient way to build
the filtered list without mutating the original.
"""
if n <= 0:
raise ValueError("n must be a positive integer")
return [
item
for index, item in enumerate(items)
if (index + 1) % n != 0
]
def main() -> None:
"""
Demonstrate the function with a simple example.
Keeping main small and focused makes the program easy to extend.
"""
data = list(range(1, 21)) # Example list: numbers 1–20
n = 3 # Remove every 3rd element
cleaned = remove_every_nth(data, n)
print("Original:", data)
print(f"After removing every {n}rd element:", cleaned)
if __name__ == "__main__":
main()
# run:
#
# Original: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]
# After removing every 3rd element: [1, 2, 4, 5, 7, 8, 10, 11, 13, 14, 16, 17, 19, 20]
#
