对于每个循环迭代，将n列复制龟列表元素

Question

我有一个我希望在每个循环结束时加倍的海龟元素列表，但它什么都不返回

level = 1

number_of_enemies = 5
enemies = []
for i in range(number_of_enemies):`
    enemies.append(turtle.Turtle())

 while True:
    for level < 4
         [for enemy in l for enemies in repeat(enemy, level)] 
         for enemy in enemies: 
              (do_stuff)
    level += 1

Answer 1

通过enemies = [generate_turtle_object_somehow for i in range(2*l)]生成一些敌人，使敌人的长度增加一倍。此外，列表推导返回结果列表，因此需要适当地分配。 代码：

level = 1
turtle = "turtle"
number_of_enemies = 5
enemies = []
for i in range(number_of_enemies):
    enemies.append(turtle+str(i+1))
#print enemies

while level < 4:
    print "level", level
    l = len(enemies)
    enemies = [turtle+str(i+1) for i in range(2*l)]
    print enemies
    print len(enemies)
    for enemy in enemies: 
        pass
    level += 1