Creating a circular matrix with one input

[Gribouillis]

There is a recursive implementation

# snail.py

LEFT, DOWN, RIGHT, UP = range(4)

def snail(start, n, m, dir):
    nd = (dir + 1) % 4 # next dir
    if not n:
        return []
    elif not m:
        return [list() for i in range(n)]
    if dir == LEFT:
        s = snail(start + m, n-1, m, nd)
        s.insert(0, list(range(start, start + m)))
    elif dir == DOWN:
        s = snail(start + n, n, m-1, nd)
        for i, row in enumerate(s):
            row.append(start+i)
    elif dir == RIGHT:
        s = snail(start + m, n-1, m, nd)
        s.append(list(range(start + m - 1, start - 1, -1)))
    elif dir == UP:
        s = snail(start + n, n, m-1, nd)
        for i, row in enumerate(s):
            row.insert(0, start + n - 1 - i)
    return s

if __name__ == '__main__':
    for row in snail(1, 5, 5, LEFT):
        print(row)

Output:
[1, 2, 3, 4, 5]
[16, 17, 18, 19, 6]
[15, 24, 25, 20, 7]
[14, 23, 22, 21, 8]
[13, 12, 11, 10, 9]

I also have another MUCH shorter recursive implementation.