如何从无限生成器列表中获取前n个元素?

时间:2019-10-12 15:41:58

标签: python

我有这个无限生成器:

def infiniList():
    count = 0
    ls = []
    while True:
        yield ls
        count += 1
        ls.append(count)

有没有办法采用前n个元素?我的意思是,我做到了:

n = 5
ls = infiniList()
for i in range(n):
  rs = next(ls)
  

输出:

print(rs)
[1, 2, 3, 4]

2 个答案:

答案 0 :(得分:1)

itertools.islice确实做到了这一点,尽管在您的示例中,您需要注意不要重复产生对不断修改的同一对象的引用:

def infiniList():
    count = 0
    ls = []
    while True:
        yield ls[:]  # here I added copying
        count += 1
        ls.append(count)  # or you could write "ls = ls + [count]" and not need to make a copy above

import itertools
print(list(itertools.islice(infiniList(), 5)))

答案 1 :(得分:0)

仅需介绍@NPE的良好答案,我需要做的就是:

import itertools

def infiniList():
    count = 0
    ls = []
    while True:
        yield ls
        count += 1
        ls = ls + [count]


print(list(itertools.islice(infiniList(), 5, 6))[0])
  

输出:

[1, 2, 3, 4, 5]