This script creates a ring of octothorpe (#) characters with optional command line arguments for radius and the width of the interior as a portion of the radius.

ring.py

import sys
from math import sqrt


def print_circle(circle):
    """
    outputs a circle that is stored as a 2D array of characters

    :param circle: 2D array of characters
    :return:
    """
    for row in circle:
        for col in row:
            print(col, end='')
        print()


def create_circle(radius, width=0.6):
    """
    Creates a ring of octothorpes of with a radius of radius and
    an interior clear space width percent of the radius.

    :param radius: radius of the circle to be drawn
    :param width: percent of radius that is interior of ring
    :return:
    """
    circle = []
    for _ in range(2 * (radius + 1) + 1):
        row = []
        circle.append(row)
        for col in range(4 * (radius + 1) + 2):
            row.append('.')

    center = (radius + 1, radius + 1)

    for row in range(len(circle)):
        for col in range(0, len(circle[row]), 2):
            distance = sqrt((center[0] - row) ** 2 + (center[1] - col / 2) ** 2)
            if radius * width < distance < radius:
                circle[row][col] = circle[row][col + 1] = '#'

    print_circle(circle)


if __name__ == '__main__':
    r = 8
    w = .7
    if len(sys.argv) > 1:
        r = int(sys.argv[1])
    if len(sys.argv) > 2:
        w = float(sys.argv[2])
    create_circle(r, w)