从列表中删除项目，并从开始到Python循环

Question

我试图在条件为真时从列表中删除项目，然后从列表的开始再次迭代。以下是我的代码：

from random import randint
x = [1,2,3,4,5]
for item in x:
    print("item is " + str(item))
    z = randint(1, 5)
    print("z is " + str(z))
    if z == item:
        x[:] = [item for item in x if item != z]
        print("Remaining list is " + str(x))
    else:
        print("Remaining list is " + str(x))

因此，例如，x列表中的我的第一个项目是1，假设Z也为1。当z == item时，我的x列表删除了第一个项目（1）并更新为[2,3,4,5]。但是我得到以下输出：

item is 1
z is 1
Remaining list is [2, 3, 4, 5]
item is 3
z is 2
Remaining list is [2, 3, 4, 5]

不是在我最近更新的列表[2,3,4,5]中从2重新启动循环，而是从第二个位置开始的循环。更新？谢谢！

Answer 1

您可以在 for循环外添加while环路，并在删除物品时重新启动for循环。

from random import randint
x = [1,2,3,4,5]
restart = True
while restart:
    restart = False
    for item in x:
        print("item is " + str(item))
        z = randint(1, 5)
        print("z is " + str(z))
        if z == item:
            x[:] = [item for item in x if item != z]
            print("Remaining list is " + str(x))
            restart = True
            break
        else:
            print("Remaining list is " + str(x))
# results
item is 1
z is 2
Remaining list is [1, 2, 3, 4, 5]
item is 2
z is 2
Remaining list is [1, 3, 4, 5]
item is 1
z is 1
Remaining list is [3, 4, 5]
item is 3
z is 4
Remaining list is [3, 4, 5]
item is 4
z is 3
Remaining list is [3, 4, 5]
item is 5
z is 5
Remaining list is [3, 4]
item is 3
z is 4
Remaining list is [3, 4]
item is 4
z is 1
Remaining list is [3, 4]

Answer 2

For循环无法按照您期望它们的方式工作，更好的是，如果您可以使用 while进行有条件检查，如以下方式：

from random import randint
    x = [1, 2, 3, 4, 5]
    loops = 0
    while loops<len(x):
        item = x[loops]
        print("item is " + str(item))
        z = randint(1, 5)
        print("z is " + str(z))
        if z == item:
            x[:] = [item for item in x if item != z]
            print("Remaining list is " + str(x))
            continue
        else:
            print("Remaining list is " + str(x))
        loops += 1

输出：

item is 1
z is 1
Remaining list is [2, 3, 4, 5]
item is 2
z is 2
Remaining list is [3, 4, 5]
item is 3
z is 1
Remaining list is [3, 4, 5]
item is 4
z is 2
Remaining list is [3, 4, 5]
item is 5
z is 1
Remaining list is [3, 4, 5]