Codewars. Python

make-a-spiral-3kyu.py

def spiralize(w):
    arr = [[0 for _ in range(w)] for _ in range(w)]
    for i in range(w):
        arr[0][i] = 1
    x,y = w-1,1
    k = w-1
    arrow = (-1,1)
    while k>0:
        for i in range(k):
            arr[y+arrow[1]*i][x] = 1
        y+=arrow[1]*(k-1)
        if k == 1:
            break
        x-=arrow[1]
        for i in range(k):
            arr[y][x+arrow[0]*i] = 1 
        x+=arrow[0]*(k-1)
        y+=arrow[0]
        k-=2
        arrow = (-arrow[0], -arrow[1])
    return arr