Spiral numbers

""" Generate number range spiral of dimensions m x n
"""

def rot_right(a):
    return zip(*a[::-1])

def spiral(m, n, start = 1):
    """ Generate number range spiral of dimensions m x n
    """
    if n == 0:
        yield ()
    else:
        yield tuple(range(start, m + start))
        for row in rot_right(list(spiral(n-1, m, m + start))):
            yield row


for m, n in (0,5), (6,0), (7,1), (1,4), (6, 7):
    print('\nSpiral %i x %i' % (m, n))
    for row in spiral(m,n):
        print(''.join('%4i' % i for i in row))

""" Output:
Spiral 0 x 5


Spiral 6 x 0


Spiral 7 x 1
   1   2   3   4   5   6   7

Spiral 1 x 4
   1
   2
   3
   4

Spiral 6 x 7
   1   2   3   4   5   6
  22  23  24  25  26   7
  21  36  37  38  27   8
  20  35  42  39  28   9
  19  34  41  40  29  10
  18  33  32  31  30  11
  17  16  15  14  13  12
"""