spiral_numeric.py

import sys
import math

def compass(n):
    cells = math.ceil(math.sqrt(n))
    maps = [[[] for _ in range(cells)] for __ in range(cells)]
    row = math.ceil(cells//2)
    col = row if cells%2 == 0 else row + 1
    pos = 'S'
    direction = {
        'N':((-1,  0), 'EN'),
        'E':(( 0,  1), 'SE'),
        'W':(( 0, -1), 'NW'),
        'S':(( 1,  0), 'WS'),
    }

    for pin in range(n):
        for path in direction.get(pos)[1]:
            motion = direction.get(path)[0]
            r = row + motion[0]
            c = col + motion[1]
            if maps[r][c] == []:
                row, col = r, c
                maps[r][c] = pin
                pos = path
                break
    return maps

def main(n):
    maps = compass(int(n))
    for m in maps:
        m = list(map(str, m))
        m = [' '*len(n) if _ == '[]' else _.rjust(len(n)) for _ in m]
        print(' '.join(m))

if __name__ == '__main__':
    main(sys.argv[1])