python - 如何找到随机数生成器的种子？

Question

我正在使用以下代码行从 l 填充 l_new 的条目。

import random

l = [11.1, 22.2, 33.3, 11.1, 33.3, 33.3, 22.2, 55.5]

l_new = random.choices(l, k=30)
print(l_new)

我总是可以通过修复种子来生成一个特定的l_new

random.seed(1)
l_new = random.choices(l, k=30)

现在，我想知道当 生成之前种子未固定时，是否有可能找到给定 l_new 的 seed l_new.

编辑:

根据下面的建议，我可以做什么

import sys
import random
l = [11.1, 22.2, 33.3, 11.1, 33.3, 33.3, 22.2, 55.5]

for i in range(10):
    seed = random.randrange(sys.maxsize)
    print("Seed:", seed)
    random.seed(seed)
    l_new = random.choices(l, k=30)
    print(l_new)

and save `seed` to retrieve the required `l_new` later on?

Answer 1

不可能从某个随机数序列中得到“种子”是不可行的。请参阅下面的梅森扭曲器的内部状态有多大。

理论上，您可以有两个不同的种子，它们产生的前 10 个数字完全相同，然后才出现偏差 - 您绘制的数字越多，出现这种情况的可能性就越小，但可能性不为 0，因此不可能出现倒数。

如果您不设置种子，它将使用从日期时间创建的种子:

random.seed(a=None, version=2)

Initialize the random number generator.

If a is omitted or None, the current system time is used [...]

seed() 只是一种设置创建随机数的 mersenne twister 的内部启动状态的方法。

但是:您可以获取此状态并将其存储并重置:

import random

random.seed(42)

numbers = [random.randint(2,22) for _ in range(15)] 
print(numbers) # now you have another interal state 

d = random.getstate()
numbers = [random.randint(2,22) for _ in range(15)] 
print(numbers) # after drawing more numbers you now have another interal state 

# go back to the last state
random.setstate(d)
numbers = [random.randint(2,22) for _ in range(15)] 
print(numbers) # you now draw the same exact numbers 

输出:

# first numbers, using system time of 1st use as seed
[22, 5, 2, 10, 9, 9, 6, 5, 19, 4, 20, 15, 3, 2, 4]
# we remebered state and create another 15
[8, 9, 18, 21, 2, 19, 8, 22, 19, 15, 9, 16, 20, 10, 2]
# we reset state to last and create the same 15 again
[8, 9, 18, 21, 2, 19, 8, 22, 19, 15, 9, 16, 20, 10, 2]

你使用哪种随机方法会影响内部状态的变化。

---

以防万一你想知道 random.seed(42) 的状态如何寻找我:

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