python - 如何在删除项目的同时循环遍历 Python 列表，直到没有剩余项目为止

Question

cycle标准库中的迭代器没有插入或删除方法，因此一旦实例化就无法修改值:

from itertools import cycle
import random

players = cycle([1, 2, 3])
while len(players) > 0:
    player = next(player)
    print(f"Player {player}'s turn")
    if random.randint(0, 6) == 1:
        players.remove(player)

# Raises TypeError: 'object of type 'itertools.cycle' has no len()'

这并不奇怪，因为它会迭代列表参数，存储每个项目，并且在完成第一个循环之前不会“知道”列表的完整内容。

是否有替代方案可以实现以下行为:

players = [1, 2, 3]
i = 0
while len(players) > 0:
    i = i % len(players)
    player = players[i]
    print(f"Player {player}'s turn")
    if random.randint(0, 6) == 1:
        players.remove(player)
    else:
        i += 1

我意识到这是可行的，但我想知道我是否缺少一种更简单的方法。

我考虑了每次删除项目后重新构建循环的方法，但这也会将位置重置为循环的开始:

from itertools import cycle

players = [1, 2, 3]
while len(players) > 0:
    for player in cycle(players):  # Problem: always starts with player 1
        print(f"Player {player}'s turn")
        if random.randint(0, 6) == 1:
            players.remove(player)
            break

但是，我无法找到在删除元素后移动到下一个玩家的简单方法。

Answer 1

如果玩家 ID 是唯一的，您可以在使用 itertools.cycle() 时维护一组要跳过的元素:

import random
from itertools import cycle

players = [1, 2, 3]
players_to_skip = set()
player_iterator = cycle(players)

while len(players_to_skip) < len(players):
    current_player = next(player_iterator)
    if current_player in players_to_skip:
        continue

    print(f"Player {current_player}'s turn")
    if random.randint(0, 6) == 1:
        players_to_skip.add(current_player)