我怎么能洗牌 python 无限生成器

Question

I have an object which I make it to be an generator:

class obj(object):
     def __init__():
         pass
     def __iter__():
         a = list(range(10))
         shuffle(a)
         for i in range(len(a)):
             yield a[i]
     .....

It can be seen that there is a shuffle operation when the generator is created. When I use itertools.cycle , this generator can works infinitely, but no shuffle operator will be done except the first time. How could I create an infinite generator behaves like itertools.cycle but can still implement shuffle each cycle ?

Answer 1

First: don't call your generator __iter__ as that is reserved for making your object instances iterable (without a call to a specific method).

For generating an infinite list of values, you would not really need to shuffle. Instead just pick a random value from the list each time. Add logic if you want to prevent the same value to be picked too soon after the previous same pick, although the more you control that, the less random it becomes.

import random

class obj(object):
     def __init__(self):
         pass
     def items(self):  # Generator
         a = list(range(10))
         while True:
             yield random.choice(a)

If your list a really is just a sequence from 0 to 9 (included), then do:

     def items(self):  # Generator
         while True:
             yield random.randint(0, 10)

If you really want all list values to have been produced before restarting, then please be aware that the last pick of the first batch might be the same as the first pick from the second batch. Anyway, that would look like this:

     def items(self):  # Generator
         a = list(range(10))
         while True:
             shuffle(a)
             yield from a

Answer 2

from random import shuffle

class my_generator():
    n = 10
    def __init__(self):
        pass

    def __iter__(self):
        a = list(range(self.n))
        shuffle(a)
        for i in range(len(a)):
            yield a[i]

    def get(self):
        my_list = []
        for i in range(self.n):
            my_list.append(self.__iter__().__next__())

        return my_list


obj =my_generator()
my_list = obj.get()
print(my_list)